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Voice communication

{VAR(flex)} supports the following types voice communication:

  • One-to-many communication:
    • Group call (from anywhere in the app)
    • Priority call
    • Dynamic group call
    • Group call to PMR over {VAR(bridge)}
  • One-to-one communication:
    • Individual simplex call
    • Direct call
    • Offline call
    • Remote microphone control (ambiance listening mode)
    • E2E encrypted call
  • Emergency call (with GPS location notification)

One-to-many communication

Group call

Push-To-Talk (PTT) is the main feature of any radio, from simple walkie-talkie handhelds to professional mobile radios such as MPT, DMR, P25 or TETRA. PTT allows a single person to reach hundreds of users in multiple channels by pushing a button. This time-honored and efficient approach is also implemented in the {VAR(company)} solution to improve communication.

Group/channel setup in {VAR(flex)} is similar to PMR terminals. During PTT use, the screen shows appropriate color behavior: light green – red – green, meaning released – requested – granted, respectively.

PTT hold timeout specifics:

Administrative configuration may define a PTT hold timeout for your user account, where you are allowed to hold the floor for no longer than a specified time and PTT is automatically released for you when the time limit is hit. This feature works in some situations but not in others – it is applicable where there is a PTT queue (floor control).
In particular, the timeout works in the following types of call:

  • Group call (except in conference channels)
  • Emergency call: only after the emergency PTT timeout ends

The timeout does not work in the following situations:

  • Conference channel
  • Individual call
  • Emergency call: before the emergency PTT timeout ends

PTT screen

The PTT screen is filled with a single PTT button. This button changes color from light green to green when someone is speaking in your group.

At the bottom, the PTT button may display information about the user that is currently talking in the channel. If the channel is free, it may show the name of the channel and the user that last spoke. That behavior is configured by the administrator in {VAR(commander)}.

In addition, the screen shows the names of available audio devices and lets you switch them.

Broadcast call

A broadcast call is similar in purpose to a group call but it is initiated by the broadcast call action instead of the PTT button. Broadcast call permissions are also administered separately from PTT permissions. Broadcast calls are normally intended for announcements and organizational information. In this type of call, the initiator subscribes specific users; these users can only listen and cannot opt out or answer.

To make a broadcast call

  1. Go to the user list by selecting it in the navigation drawer.
  2. Tap the Select users for broadcast call icon Select users for broadcast call icon.
  3. In the view that opens, select the users you need, and tap the same icon again.

PTT is available throughout {VAR(flex)}

Channel talk is the central functionality of the {VAR(company)} system. By default, you can start a channel talk from any operational interface using the PTT button. Even if you are focused on the map interface, the PTT button is always at hand. This feature has the advantage of providing easy and fast communication anytime in any context.

Priority call

The priority call is one of the major features of modern professional communication. It allows users with a higher priority to interrupt individual or group call communication at any time and get through with important information. The levels of priority are unlimited in the {VAR(company)} system and can be individually set up for each user in {VAR(commander)}.

Dynamic group call

A dynamic group is formed on the spot from selected {VAR(flex)} users. A dispatcher assigns a dynamic group to selected users in {VAR(rodon)} to create an ad-hoc channel for immediate communication needs. This feature is designed for command and control centers to provide a flexible operational tool for team organization and quick response.

A dynamic group exists until the last {VAR(flex)} user leaves the dynamic group call channel.


You can listen to multiple channels at the same time if this functionality is enabled for you by the administrator in {VAR(commander)}. If this is the case, enable multilistening for each group you need. Do the following:

  1. In the group list, long-tap the icon to the left of the group. This enables listening for the group, and the icon changes accordingly.
  2. If you long-tap the icon again, this either mutes the group or disables listening for it, depending on administrative configuration.

Groups for which listening is enabled have a green circle icon on the left.

Accidental PTT use can be prevented for specific channels

The administrator can configure a channel so that only deliberate group talk occurs in it. Before you can use PTT in such a channel, you have to select that channel. This starts a timer, and you have to press PTT before the timer runs out; otherwise, you'll need to select the channel again.

Group call to PMR over {VAR(bridge)}

Any PMR Network such as TETRA or MOTOTRBO can be extended with the {VAR(company)} solution or become integrated as its complement. Voice communication between PMR and {VAR(company)} is possible through {VAR(bridge)}. If {VAR(bridge)} is configured in your environment, voice communication involving both networks ({VAR(company)} and PMR) is done through special allocated groups using regular group calls. The {VAR(bridge)} configuration is transparent to you as a {VAR(flex)} user – use the PTT button and talk, whether your audience is in the {VAR(company)} network or in the PMR network.

One-to-one communication

Individual call

This is the equivalent of a one-to-one simplex call, providing secure point-to-point communication. The two users can be anywhere in the network or in different channels.

To make an individual call

  1. Go to the user list by selecting it in the main menu.
  2. Tap the user you need and then tap the individual call icon. The available action icons are above the user list interface when a user is selected.
  3. Wait for the other user to accept your call, and then use the PTT button to start talking.
What happens during an individual call:

The calling party sees the Outgoing Call window and hears outgoing call ringtones.
The party being called can hear incoming call ringtones and see the incoming call notification.
The calling party has to wait until the call is accepted or drop the call using the red phone button.
The party being called can accept the incoming individual call or drop it using the red phone button.

If the user could not answer the call, they get a notification message about the missed call.

Direct individual call

This is a call to another user without prior notice. The user who receives the call immediately sees the icon of the established connection on the device screen. This type of call does not require confirmation from the receiving party.

To make a direct call

  1. Go to the user list by selecting it in the main menu.
  2. Tap the user you need and then tap the direct call icon. The available action icons are above the user list interface when a user is selected.

If the corresponding parameter is configured by the administrator in {VAR(commander)}, a progress bar appears and will run out unless one of the parties involved in the call presses the PTT button. The call is interrupted if the progress bar runs out.

Video call

Users can exchange video calls in the {VAR(company)} system. During a video call, each of the participants can mute and unmute their microphone, and switch between the front and rear camera view.


Make sure that you have a stable Internet connection when placing or receiving video calls. The quality of a video call depends on the contact with the weaker connection.

To make a video call

  1. Go to the user list by selecting it in the main menu.
  2. Tap the user you need and then tap the video call icon. The available action icons are above the user list interface when a user is selected.
  3. Wait for the other user to accept your call.
Receiving a video call:

When someone video calls you, you see an INCOMING VIDEO CALL screen, where you can accept or decline the call.

PTV call

This is a video call that does not require confirmation from the receiving party. A PTV call is declined if the receiving party is already in a call.

To make a PTV call

  1. Go to the user list by selecting it in the main menu.
  2. Tap the user you need and then tap the PTV call icon. The available action icons are above the user list interface when a user is selected.
  3. Use the PTT button to take your turn transmitting video and voice.

Offline user call

You can initiate an individual call to an offline user. In this case the system automatically accepts the call and records your message. Use the PTT button to record the message. Your records appear in the history and will be available when user is online.

If you get such a call while you are offline, you can listen to the recorded message by tapping the play button in the top right corner when you come back online.

Muting users

You can mute specific users in a similar way to how you disable listening for groups. This doesn't change the muted users' configuration or permissions in any way; it only makes sure you don't hear them in {VAR(flex)}.

To mute or unmute a user, long-tap the icon to the left of that user.

Emergency call

The emergency call feature is integrated into any mobile client and can be useful in emergency situations. Emergency calls do not require acceptance by the operator. They get through automatically to allow the user to talk straight away without any delay. This feature is designed for immediate interaction with the operator of a command and control centers (who are normally {VAR(rodon)} users). When an emergency call is in progress, {VAR(flex)} sounds an appropriate emergency audio signal and gets an emergency message with GPS coordinates (if GPS is enabled on the caller device).

The emergency message is highlighted red. All emergency messages contain the reason that caused the emergency, and it is logged in the emergency journal.

There are a variety of situations that qualify as emergencies: simple emergency (SOS) call, any LWP emergency (Periodic Check, Mandown, No Movement, Impact or Fall Detection, Battery Level Warning or Alarm), zone statuses (if a zone is empty, if a user goes in or out, if a user connects or disconnects, if a user stays in the zone for a certain time), and so on.

All emergency messages appear in the emergency journal, which can be enabled or disabled by the administrator in {VAR(commander)}, no matter what caused the emergencies.

When an emergency call is started, {VAR(rodon)} can toggle a distress sound on the caller device.

When an emergency call is completed, the user is moved to the group where that user was before the call.

There are a few emergency-related options that an administrator may configure for users in {VAR(commander)}, listed below. You cannot change these options in {VAR(flex)}.

  • Prevent stop emergency If this is enabled, you cannot stop an emergency call once you have initiated it. To finish the emergency call in this case:
    1. Tap and hold to suspend the emergency call.
    2. Wait for the {VAR(rodon)} operator to confirm the call end. ({VAR(rodon)} shows a confirmation prompt that has to be closed.)
  • Mute outgoing emergency
    Mutes the sound of the emergency popup that appears when the user sends an emergency.
  • Max emergency volume
    Maximizes the volume for an outgoing emergency when the user sends it.

Making emergency calls


Make sure GPS functionality is enabled on your device if you use {VAR(flex)}. If your GPS is turned off, your emergency messages will contain no GPS coordinates.

You can make an emergency call in the following two ways:

  • By tapping the Emergency symbol on the PTT screen
  • By opening the Emergency tab in the main menu and holding the Emergency symbol

In either case, you get a popup that says "Click to Cancel Emergency Call" and shows a countdown. This helps prevent false emergencies started by mistake. If you tap the popup before the end of the countdown, the emergency call is cancelled. If the countdown completes uninterrupted, the emergency call starts and the emergency message is sent.

If you use a smartphone with dedicated hardware buttons (for example, Sonim XP7), make an emergency call by pressing and holding the hardware emergency button (usually red).


Use emergency calls only for emergency reasons; do not abuse the feature where a direct call would suffice. Emergency calls are intended for users who are in need of urgent assistance. In addition, emergency calls affect the performance of {VAR(rodon)} and {VAR(flex)} more than other types of call do.
The {VAR(company)} development and marketing teams accept no liability for any loss or damage by malfunction or misuse. Users need to ensure that their emergency calls sent to {VAR(rodon)} by {VAR(flex)} can be received by the monitoring administrator.
Before production use, do a coverage network test and physical test of the device, including moving it from one site to another. The monitoring administrator must ensure that their supervised users follow very strict operating instructions. The users and the monitoring administrator should be aware that they cannot rely fully and solely on this product to ensure their safety and security; they can only use this product as an auxiliary, supplemental aid to assist them in knowing the user is in need of assistance.

E2E encrypted call

{VAR(flex)} offers an additional security mechanism called end-to-end encryption (E2EE), implemented on top of built-in TLS. E2EE prevents potential eavesdroppers from being able to access the encrypted conversation even if they manage to intercept the communication channel. E2EE in {VAR(company)} provides a way of communication where only the communicating users with matching key pairs (encryption and decryption keys) can hear the voice messages. It is an additional level of protection to ensure that no third parties without the keys can capture the voice data being transmitted or store it.

When you make an E2EE call, you need both an encryption key and a decryption key. Agree on the keys with the other user in advance. You can also share the keys with other users from the user list or from the map.

Establishing a secure connection

  • The E2EE feature must be enabled for both participating users by the administrator in {VAR(commander)}.
  • For security reasons, all recorded E2EE calls can be played back from the history only if the appropriate keys are provided.
  • Emergency calls and remote listening audio are never E2E encrypted.

Encrypt both devices and share the keys with the user you need. For that, take the following steps:

  1. Make sure Enable PTT Encryption is enabled in {VAR(flex)} on both devices.
  2. Come up with a key. Any string can be used as the key. Save it as your encryption key in the settings.
  3. Select the user you need and share the encryption key with them. Instruct the user that they should save it as their decryption key.
  4. Confirm that the other user has accepted and saved the key.
  5. Obtain the other user's key and save it as your decryption key in the settings.

If there is a padlock icon on the PTT button, this indicates that an encryption key is set. This icon has two states:

  • Closed – encryption is active
  • Open – encryption is inactive

To toggle the use of encryption on or off, long-tap the padlock icon.

If you clear the Encryption Key and Decryption Key fields and tap Save, this has the effect of turning off encryption on the device.