Emergency
General
MOTOTRBO offers a variety of emergency handling strategies that addresses the needs of customers. In its basic form, MOTOTRBO provides the ability for a radio user in distress to send a confirmed emergency alarm message, and emergency voice to a user or group of users. The emergency alarm message contains the individual radio ID of the initiator, and their location if available.
Upon reception of an emergency alarm, the other user(s) receives audible and visual indications of the emergency and the initiating radio ID is displayed. If a dispatch and location tracking application is used, the location of the initiating user can be displayed. Depending on configuration, emergency voice may follow between the initiator and the supervisor. Once the supervisor handles the emergency situation (solves the problem), they would have to clear the emergency on the supervisor radio. Once the initiator clears their emergency on the initiator radio, the emergency is considered over.
Emergency can be triggered by pressing a programmed button on the radio; pressing a switch connected to a mobile radio; by triggering the man down function or by triggering (not responding to) Lone Worker.
Emergency Search Tone
This Emergency Search Tone can be configured in all current high tier MOTOTRBO radios, and can be enabled or disabled via CPS/RM configuration. It is not available in low tier models like the DP1400 or SL1600.
If enabled, when the radio initiates an emergency, it plays out a loud and attention grabbing tone (Emergency Search Tone), to help people around to locate and identify the emergency initiator. This Emergency Search Tone is for the emergency initiating radio only, and not for the emergency receiving radios. This tone starts when the emergency starts and ends when the radio exits the emergency. The tone is temporarily suspended, when the radio is transmitting or receiving voice/data/CSBK calls. If enabled, this Emergency Search Tone is played out regardless if the CPS “All Tone Disabled” option is turned on or not.
The Emergency Search Tone feature is disabled on a transmitting radio whenever the Emergency Call is acknowledged by a Receiving/Acknowledging radio. If the Emergency Call is not acknowledged, the Emergency Search Tone is emitted by the transmitting radio and continues to be emitted as expected.
This tone is mutual exclusive with the Silent Emergency feature. That is, if the Silent Emergency is enabled for the radio, this feature is disabled automatically regardless if this tone is CPS enabled or not. Also, it is CPS configurable to specify where to route this Emergency Search Tone/incoming voice, either the radio’s internal speaker or the accessory. When an accessory is not attached, it is always routed to the radio’s internal speaker automatically.
TX RX Cycles
Radios can be configured to automatically transmit for a certain number of seconds, then receive then transmit again. This allows a radio user, who is incapacitated or unable to operate the PTT, to transmit some form of message. Alternatively, it is possible for a supervisor or coworker to listen for any tell-tale sounds to determine wha is wrong (e.g. people screaming; loud bands etc.).
There are three settings for this:
- TX cycle time. How long the radio will transmit for.
- RX cycle time. How long the radio will receive for, between transmissions.
- Number of cycles. How many transmit-receive cycles the radio will perform when emergency is triggered.
This feature can only be used if Emergency Alarm with Voice to Follow is enabled.
In Single Site and IP Site Connect
Note that a radio does not roam, when reverted to a channel due to an emergency, or when Active Site Search is disabled. See Roaming for details on the interactions between emergency and roaming.
On a mobile radio, the Emergency Alarm function can be assigned to any of the programmable buttons, whereas for the portable radio the Emergency Alarm can only be programmed on the orange button. The Emergency Alarm can also be triggered externally through a footswitch, in a vehicle installation for example, or any other applicable accessory. Pressing the emergency button causes the radio to enter emergency mode, and begin its emergency process.
When a user presses the Emergency button, the radio gives audible and visual indications to show that it has entered emergency mode. There is a CPS/RM configurable option available, referred to as Silent Emergency, which suppresses all indications of the emergency status on the user’s radio. This feature is valuable in situations where an indication of an emergency state is not desirable. Once the user breaks radio silence by pressing the PTT and speaking, the Silent Emergency ends, and audible and visual indications return.
When the user’s radio is in emergency mode, various other features are blocked that may distract them from communication with the supervisor or dispatcher. For example, the user is not able to initiate other features such as Scan, Private Call, or other command and control functions.
Once the emergency is complete (for example by turning the radio off and on again, or long/short press of the emergency button depending on the radio configuration) these abilities return.
Call Process
The emergency sequence is generally made up of two major parts:
- The signaling
- The following voice call
The emergency alarm is sent first, and depending on configuration is commonly followed up by an Emergency Call.
An emergency alarm is not a data service, but rather a confirmed command and control signaling that is sent to a group. More than one radio can be configured on the system to monitor that group, and be designated to acknowledge emergency alarms for that group. These radios are considered acknowledging supervisors. There is no user level acknowledgment. The supervisor radio automatically acknowledges the emergency, and provides an alert to the supervisor radio user. There are other radios that are designated to only monitor emergency alarms, but are not permitted to acknowledge them; these users are commonly referred to as non-acknowledging supervisors. Thus, sending the emergency alarm to a group allows for multiple supervisors to receive the emergency alarm indication. It is important that only one acknowledging supervisor should be configured per group and slot; otherwise there may be contention between the acknowledgements.
The supervisors retain a list of received emergency alarms so that they can keep track of multiple emergencies. Once cleared, the emergency alarm is removed from the list, and the next one is displayed. These emergencies are displayed in a last-in-first-out sequence. The supervisor has the ability to hide the emergency alarm list, so he can contact service personnel to attend to the received emergency situation. The channel where the emergency alarm was received is displayed to aid the supervisor when changing channels.
If the user follows up the Emergency Alarm with a voice call while in the emergency mode, his transmission contains an embedded emergency indication. Any radio user can be configured to display this embedded emergency indication. Emergency Calls are always processed with an admit criteria of Always. This allows the Emergency Call to transmit regardless of the current channel activity. If there is another radio currently transmitting, contention may occur.
Unmute Option
The initiating radio supports a feature that is tied to silent emergency and the Emergency Call. The “Unmute Option” prevents the radio from receiving voice traffic after initiation of a Silent Emergency. In situations where an indication of an emergency state is not desirable, it is important to be able to mute incoming voice, that may give away the initiators emergency state. Once the user breaks radio silence by pressing the PTT and speaking, the radio returns to its normal unmute rules.
Silent emergency and the unmute options have no effect on data. It is the responsibility of the end user to make sure data is not sent to a terminal that would divulge any emergency state. Transmission of data does not clear Silent Emergency.
Emergency Revert
The channel and group on which a user transmits his emergency is crucial to properly contacting a supervisor. MOTOTRBO offers the ability for a user to transmit the emergency on a selected channel or to automatically change to a predetermined channel to transmit his emergency. Transmitting an emergency on a selected channel (referred to as a “tactical” emergency) is often useful on small systems where there are only a few groups of users. Each group has its own specified user that handles emergencies.
Automatically changing to a predetermined channel, referred to as “reverting”, is often useful in systems that have a dispatch style emergency strategy. Users in various groups and channels are configured to revert to a specific channel and group to process an emergency. This allows one user to monitor an “Emergency” group, and all other users revert to him in case of an emergency. This minimizes the possibility of supervisors missing emergencies on one channel, while monitoring other channels. After the emergency is cleared, all users revert back to the selected channel they were on before the emergency. In MOTOTRBO systems, the Emergency Revert Channel is configured in portable and mobile radio CPS at the Digital Emergency Systems settings.
Emergency Alarm Only
When configured for Emergency Alarm Only, the emergency process only consists of the emergency alarm part. The number of emergency alarm attempts and their admit criteria are configurable, and can even be set to retry indefinitely. The number of alarm attempts are controlled by CPS parameters in the Digital Emergency System settings. These parameters include the number of polite and impolite retries. The alarm is initially sent regardless of channel activity, and once the configured impolite attempts are exhausted, the polite retries are executed when the channel is idle. The Emergency Alarm Only ends when:
- An acknowledgment is received
- All retries are exhausted
- The user manually clears the emergency, or
- The user pushes the PTT.
No voice call is associated with the emergency when operating as Emergency Alarm Only. Pressing the PTT clears the emergency, and a standard voice call is processed.
Emergency Alarm and Call
When configured for Emergency Alarm and Call, the emergency consists of the emergency alarm process followed by the ability to perform an Emergency Call. The number of emergency alarm attempts and their admit criteria are configurable, and can even be set to retry indefinitely. The alarm is initially sent regardless of channel activity, and once the configured impolite retries are exhausted, the polite retries are executed when the channel is idle.
Emergency alarm stops when:
- An acknowledgment is received, or
- All retries are exhausted.
The radio still remains in an emergency state. Any follow up PTT initiates an Emergency Call, and the call includes an embedded emergency indication. If the user presses the PTT before the radio sends an emergency alarm, the radio stops sending the alarm, and starts the Emergency Call. While in the emergency mode, all subsequent voice transmissions are Emergency Calls. The user remains in emergency mode until he manually clears emergency. The only way to reinitiate the emergency alarm process is to reinitiate the emergency.
Emergency Alarm with Voice to Follow
When configured for Emergency Alarm and with Voice to Follow, the emergency consists of sending a single emergency alarm, and followed by an automatic transmission of an Emergency Call. This is referred to as hot microphone.
The radio only sends one emergency alarm regardless if there is channel activity, and then without waiting for an acknowledgment the radio immediately activates the microphone and initiates an Emergency Call without the need of the user pressing the PTT. The duration of the hot microphone state is configurable through the CPS in the Digital Emergency Systems settings. This transmission is considered an Emergency Call, and therefore includes the embedded emergency indication. Once this hot microphone duration expires, the radio stops transmitting, but remains in the emergency mode.
Any follow up PTT initiates an Emergency Call, and includes the embedded emergency indication. The user remains in the emergency mode until he manually clears his emergency. The only way to reinitiate the emergency alarm and the hot microphone is to re-initiate the emergency. It is important to note that when configured for Emergency Alarm with Voice to Follow, the radio continues to transmit voice for the duration of the provisioned hot microphone timer. Since voice has priority over data, any data is queued while voice is transmitting, including the GPS update that was triggered by the emergency. The GPS data cannot be delivered until after the radio stops transmitting voice, and after the repeater hangtime has expired. The GPS data has no additional priority over other data queued in the radios, or over any traffic on the channel. Therefore, its delivery may be delayed if the radio in emergency has pending data queued or if the channel is busy processing other traffic.
It is recommended when utilizing Emergency Alarm with Voice to Follow and GPS, that the hot microphone timer be at maximum 30 seconds. There are a few reasons for this. First of all, data messages do not stay in the queue forever, 30 seconds is short enough so to give the GPS data a chance to be transmitted without timing out. Second, if the hot microphone timer is longer than 30 seconds, and the GPS update rate is around the same value, then ther GPS messages may start to fill up in the queue while the voice transmission is processing. This not only occurs with the radio in emergency, but with all other radios since the channel is busy. Therefore when the voice call ends, all radios attempt to access the channel with their GPS data which increases the likelihood of collisions and lost messages. Finally, understand that while the user is transmitting due to its hot microphone timer, there is no way to communicate back to them. Most users can explain their situation in less than 30 seconds and require some feedback from the emergency dispatcher much sooner. That is why it is recommended to keep this value low and if additional monitoring is required, the remote monitor feature can be utilized. Only use a long hot microphone timer in specialized applications.
Also, since the emergency alarm itself is not acknowledged nor retried, its reliability is less than that of the standard Emergency Alarm and Emergency Alarm Only and Call. These considerations should be taken into account when choosing to operate with Emergency Alarm with Voice to Follow.
Emergency Voice Interrupt for Emergency Alarm
When enabled in a radio, Emergency Voice Interrupt is used during the initiation of an emergency condition when an interruptible voice transmission is already taking place on the channel. When an emergency is initiated with Emergency Voice Interrupt enabled, the radio attempts to interrupt an ongoing, interruptible voice transmission on the channel. The radio then uses the established procedures for either Emergency Alarm or Emergency Alarm with Call, depending upon the CPS configuration. For the Emergency Voice Interrupt for Emergency Alarm feature, the radio is not required to be a member of the voice call being interrupted.
Note that for Emergency Voice Interrupt for Emergency Alarm feature to operate consistently, all radios using the channel should be provisioned with the ability to be interrupted. However, not all need to be provisioned with the Emergency Voice Interrupt for Emergency Alarm capability.
If some radios are provisioned without the ability to be interrupted (for example, normally desirable for a supervisor’s radio), then those radios’ transmissions cannot be interrupted and the radio user instead transmits the Emergency Alarm in accordance with the configuration of the polite and impolite Emergency Alarm fields in the CPS, if Emergency Alarm is attempted while receiving another radio’s uninterruptible transmission.
If the interruption of the voice transmission is successful, the radio uses the established procedures for either Emergency Alarm or Emergency Alarm with Call, depending upon the CPS configuration, once the channel has been cleared. Depending on the radio’s CPS configuration, the radio user whose transmission was interrupted may or may not receive a Talk Prohibit Tone until the PTT is released.
If the interruption of the voice transmission fails, the radio then uses the established procedures for either Emergency Alarm or Emergency Alarm with Call, depending upon the CPS configuration. However, the probability of success diminishes because the original voice transmission had not been successfully cleared from the channel.
If the voice call on the channel is not transmitting an interruptible voice signal, the radio uses the established procedures for either Emergency Alarm or Emergency Alarm with Call, depending upon the CPS configuration, again with a lower probability of success.
Emergency Voice Interrupt for Emergency Voice
The Emergency Voice Interrupt feature, when enabled in a radio, is used during the initiation of an emergency voice transmission, primarily when an interruptible voice transmission takes place on the channel and the radio does not belong to that voice transmission. The radio attempts to interrupt the voice transmission, and then uses the established procedures for Emergency Voice Transmissions, when all of the following conditions are met:
- Emergency Voice Interrupt is enabled.
- The radio is in an emergency condition (for example, the designated Emergency button was pressed previously).
- Another radio’s interruptible voice transmission is taking place on the channel.
- The radio in the emergency condition does not belong to the other radio’s voice transmission (that is, the radio in the emergency condition is not receiving the other radio’s voice transmission).
- The radio user in the emergency condition requests an Emergency Voice Transmission.
The Emergency Voice Interrupt for Emergency Voice feature is not used when the radio belongs to the voice call that is being interrupted. Instead, when the radio belongs to the call on the channel (that is, the radio that is receiving the voice transmission), the “In Call Criteria” is used rather than the Emergency Voice Interrupt feature. This is because some systems may disallow radios to interrupt any call to which they belong. In this case, the user must wait until the receiving transmission has finished, before beginning their Emergency Voice transmission.
The Emergency Voice Interrupt for Emergency Voice feature is also capable of interrupting an All Call provided the All Call is transmitting interruptible voice.
For this feature to operate consistently, all radios using the channel should be provisioned with the ability to be interrupted. However, not all need to be provisioned with the Emergency Voice Interrupt for Emergency Voice capability. If the radio succeeds at interrupting the voice transmission, the radio uses the established procedures for Emergency Voice Transmissions, once the channel has been cleared. Depending on the radio’s CPS configuration, the radio user whose transmission was interrupted may or may not receive a Talk Prohibit Tone until the PTT is released. If the radio fails to interrupt the voice transmission or the voice transmission is not interruptible, the radio also uses the established procedures for Emergency Voice Transmissions. However, the probability of success diminishes because the original voice transmission had not been successfully cleared from the channel.
In Capacity Plus
No Revert in Capacity Plus
Single Site Capacity Plus and Multi-Site Capacity Plus do not support a revert channel for emergency (since they are both trunked systems).
The start of an Emergency Call is announced over all busy channels. This allows a listening radio that is interested in joining the Emergency Call, to leave its channel/call and join the Emergency Call. A radio is interested in an Emergency Call if the emergency group is either the TX-Group, or is in the RX-Group list of the radio. A radio listening to an Emergency Call (for example, Emerg-1) joins another Emergency Call (for example, Emerg-2), only if the Emerg-2 is a TX-Group or is higher up in the RX-Group List for that personality.
Capacity Plus Single Site and Multi-Site systems ensure that an Emergency Call should start on a channel where the users monitoring the Emergency group are present. There are some behavior differences in software versions R01.05.00 through R01.07.00. This is shown in the following flowchart:
Note that in software version R01.05.00, an Emergency Call may not be serviced if all of the following scenarios occur:
- All Trunked Channels are busy.
- A call for the emergency talkgroup is active on a channel.
- A radio powers on or joins the system after a long fade and the radio initiates an Emergency Call. In this instance, there is no radio to service the Emergency Call on the busy Rest Channel.
There are three major methods to process the emergency alarm and the Emergency Call; all are configurable through the CPS/RM. They are Emergency Alarm Only, Emergency Alarm and Call, and Emergency Alarm with Voice to Follow.
Multi-Site Capacity Plus handles an Emergency Call at the source site in the same way as in a R01.07.00 Capacity Plus Single Site system. If a Rest Channel is busy at a destination site, and the call is interruptible, then the ongoing call is interrupted for the Emergency Call to proceed. However, if the ongoing call is not interruptible, the Emergency Call starts impolitely. Note that the impolite Emergency Call is sent to the sites associated with the emergency talkgroup.
In Capacity Max
Capacity Max enables a radio user in distress to send an emergency alarm, and optionally emergency voice, to a talkgroup monitored by a voice console operator. Upon reception of an emergency alarm, the dispatch application provides an audible and visual indication of the emergency and the initiating radio ID is displayed. Depending on configuration, emergency voice may follow between the initiating radio and the console operator. When the condition that led to the emergency alarm is resolved, the console operator clears the alarm locally. When the initiating radio user clears the emergency on the initiating radio, the emergency is terminated.
Radios can receive emergency alarms/calls and the talkgroup, to which emergency calls are directed, must therefore be monitored by another radio or voice application.
Emergency Initiation
A mobile radio can have the emergency button programmed on any of the programmable buttons, whereas a portable radio can only use the orange button as the emergency button. An emergency can also be triggered externally through a footswitch, a mobile application, or any other applicable accessory. ressing the emergency button causes the radio to enter emergency mode and begin its emergency process.
Alarm Type
The alarm type determines the ergonomics of the initiating radio upon entry to emergency mode.
Regular
When a user initiates a regular emergency, the radio provides an audible and visual indication to show that it has entered emergency mode. The audible indication is to notify the radio user of successful entry to emergency mode.
Silent
When a user initiates a silent emergency, the radio suppresses all indications of the emergency status on the initiating user’s radio. In addition, all received voice is muted. The voice is muted so that responses from the voice console do not inadvertently indicate the emergency state. This feature is valuable in situations where an indication of an emergency state is not desirable.
When the user breaks radio silence by pressing the push-to-talk (PTT) button and speaking, the silent emergency ends, audible and visual indications return, and the radio returns to its normal unmute rules.
Silent emergency has no effect on data. It is the responsibility of the end user to make sure data is not sent to a terminal that would divulge any emergency state. Transmission of data does not clear a silent emergency.
Silent with Voice
When a user initiates a silent emergency with voice, the radio suppresses all indications of the emergency status on the initiating user’s radio, but received voice is not muted. This feature is valuable in situations where an indication of an emergency state is not desirable. When the user breaks radio silence by pressing the PTT button and speaking, the silent emergency ends, and audible and visual indications return.
Silent emergency has no effect on data. It is the responsibility of the end user to make sure data is not sent to a terminal that would divulge any emergency state. Transmission of data does not clear a silent emergency.
Emergency Talkgroup
Emergency alarms and emergency voice are addressed to a talkgroup. The selection of which talkgroup to direct emergency calls to, makes a major difference in the overall operation of the emergency. The emergency talkgroup is configured as the contact name in the emergency system set within Radio Management (RM).
Tactical
Sending an emergency on the currently “selected” talkgroup (sometimes referred to as a “tactical” emergency) allows everyone in the currently selected talkgroup to monitor the emergency situation.
Each talkgroup may have a dedicated dispatcher that handles emergency situations, or the entire group may need to be notified that someone in the talkgroup is in emergency.
In a system with many talkgroups, a tactical configuration requires the dispatcher to monitor every talkgroup for emergencies, which could become cumbersome. In addition, the remaining members of the talkgroup must yield use of the talkgroup to the individual in emergency.
Reverting
Sending an emergency on a predetermined talkgroup (referred to as "reverting”) allows users to leave their currently selected talkgroup and communicate to the dispatcher on a dedicated emergency talkgroup.
This reverting function allows a dispatcher to monitor the dedicated emergency talkgroup and have all other users revert to the dispatcher in case of an emergency. This function minimizes the possibility of supervisors missing emergencies on one talkgroup while monitoring other talkgroups. It also allows a clear channel of communication for the user initiating the emergency and the dispatcher. Other radio users may not be aware of the emergency situation unless they monitor the dedicated emergency talkgroup.
After the radio user clears the emergency, the radios revert to the talkgroup they selected before the emergency occurred. If the radios revert to a dedicated emergency talkgroup, that talkgroup must be statically assigned to the
MNIS VRC and Data gateway sites. If the revert emergency talkgroup was not previously affiliated, the radio affiliates to the emergency talkgroup before starting its emergency procedures.
Reception of an Emergency Alarm or Call
Emergencies are best received and handled at voice consoles. The larger display allows the dispatcher to effectively handle numerous simultaneous emergencies. The methods vary depending on the console vendor.
Emergency Alarm Indication
The radio retains the last received emergency alarm. Once cleared, the emergency alarm is removed from the radio. The channel where the emergency alarm was received is displayed to aid the supervisor when changing channels. Delivery of emergency alarms is only confirmed inbound over the air to the system. They are not confirmed outbound to the radios. Only radios with this option enabled, and that are monitoring the control channel when the emergency alarm is initiated, provide the emergency alarm indication.
Emergency Call Indication
If a user follows the emergency alarm with a voice call while in emergency mode, that user’s transmission contains an embedded emergency indication. Radios can be configured to display this embedded emergency indication when they receive an emergency call. The indication is not persistent. The indication is only present while the radio is receiving an emergency call.
Transmission of Location Information During an Emergency
A location equipped radio can send its location to a location data application when an emergency is triggered. The location data application requests the radio to send location on the emergency event when it requests periodic location updates.
Feature Interaction During an Emergency
When a radio is in emergency mode, features that may distract that user from communication with the supervisor are blocked. For example, the user cannot initiate an individual call or talkgroup call from the address book, or other command and control functions. In addition, any other receive talkgroups that were previously configured for that user are not monitored. When the radio exits emergency mode (for example, after the user turns the radio off and on, after a long or short press of the emergency button, depending on the radio configuration), the features blocked during the emergency return.
Prioritization of Emergencies in Capacity Max
Capacity Max supports 10 levels of Call Priority. Only 2-10 is available for selection. Emergency is automatically allocated call priority 1. If the system is busy, the lowest priority call may be preempted (cleared down) if no traffic channel (slot) is available on the site to process this call.
Call Preemption at Busy Sites
If no trunked channels are available, the system interrupts (preempts) ongoing calls and grants the emergency call. If a radio is transmitting on the preempted channel at the same site as the emergency initiator, the system directs that radio to immediately stop transmitting, which prevents interference with transmissions by the emergency initiator.
Radio transmissions that were occurring on the preempted channels at other sites are not interrupted, but their transmissions are not repeated. When any interrupted radio dekeys, it returns to the control channel. Other calls are not interrupted.
Emergency Calls Announced on Trunked Channels
The system announces ongoing emergency calls in the embedded signaling of other ongoing calls. This function allows radios to join the emergency call even while participating in other calls. In order to use this feature, radios must have the emergency talkgroup as their primary talkgroup or in their talkgroup receive list.
Longer Emergency Call Hangtime
The system allows for emergency calls to have a longer call hangtime than other talkgroup calls. A longer call hangtime holds the assigned trunked channel longer. This function aids in call continuity and decreases access time for in-call retransmissions. The emergency call hangtime is configurable within Radio Management.
Increased Number of Channel Access Attempts
The system allows for emergency alarms and calls to have more channel access attempts than other call types. Allowing more channel access attempts increases the opportunity for emergency calls and alarms to access a channel during poor coverage or heavy call volumes.
Interaction Between Voice to Follow and Location on Emergency in Capacity Max
When configured for Emergency Alarm with Voice to Follow, the radio continues to transmit voice for the duration of the provisioned hot microphone timer (TX Cycle Time). Because voice has priority over data, any data is queued while voice is transmitting, including the location update that triggered the emergency. The location data cannot be delivered until after the radio stops transmitting voice and after the repeater hangtime has expired. The location data has no additional priority over other data queued in the radios, or over any traffic on the channel. Therefore, if the radio in emergency has pending data queued or if the channel is busy processing other traffic, its delivery may be delayed.
When Emergency Alarm with Voice to Follow and location on emergency are in use, the hot microphone timer should be set at maximum 30 seconds. Because data messages do not stay in the queue forever, 30 seconds is short enough to give the location data a chance to be transmitted without timing out. Also, if the hot microphone timer is set to an interval longer than 30 seconds, and the location update rate is close to the same value, other location messages may start to fill up in the queue while the voice transmission is processing.
When a user is transmitting during the hot microphone timer interval, there is no way to communicate back to that user. Most users can explain their situation in less than 30 seconds and require some feedback from the emergency dispatcher much sooner. Therefore, a short timer interval is recommended, and if additional monitoring is required, the remote monitor feature can be utilized. Long timer intervals should be used only in specialized applications.