Site Tools

Voice support

The NetModule Router Series NB2000 and NB3000 support voice and audio communication with two extension:

  1. Voice-License (“V”) GSM-Voice to VoIP/SIP to make or receive PSTN voice call over the mobile network.
  2. Audio (“A”) stereo line-in/out to VoIP/SIP to connect audio signals directly to the device. Typical microphone and loudspeaker via external amplifier.
  3. Push-to-Talk (“Ap”) mono line in/out to connect audio signals directly to the device, 1/1 digital in/out e.g. for call & ring signaling

Basic concept

An endpoint is a SIP/VoIP device like

  • Internal GSM-Voice
  • Internal Audio-Interface
  • External SIP-Phone, PBX, door station etc.

To establish a call two steps are needed:

  1. Signalling = establish a call
  2. Call-Routing = making the connection

Simple behaviour can be configured by the Web-GUI. For more complex applications the SDK can be used.

Voice gateway configuration via Web GUI

Using the router with a SIP phone client.




^ Parameter ^ Voice Gateway Endpoint Types ^
| Voice-Over-Mobile | Endpoint for GSM/UMTS/LTE calls (can be used for calls to mobile or landline phones)|
| SIP (registrar)| SIP endpoint which can be a client registered to our registrar |
| SIP (direct)| Endpoint for calls directly routed to a SIP agent without registration |
| SIP (user-agent) | Endpoint acting as SIP user agent towards a remote registrar |
==== Endpoint types ====


Routing modes

SDK scripts

Endpoints are represented as structs

struct(3): {
	.id = int: 54321
	.desc = string[5]: "vom://Vom1"
	.state = string[4]: "busy"
	.volume = = int: 7


  • Sip1 First SIP subscriber
  • Vom1 First Voice-Over-Mobile
  • Aud1 First Audio device
  • sip:⁄⁄user@192 .168.1.254:5060 SIP address


  • busy endpoint is already holding a call
  • available endpoint is ready to take a call

Calls are represented as structures which may look like:

struct(5): {
	.id = int: 12345
	.state = string[7]: "dialing"
	.calling = string[24]: "sip://user@192 .168.1.254:5060"
	.called = string[22]: "vom://+123456789 @Vom1"

The following states are possible:

  • routing call is in routing state
  • dialing call is in dialing state
  • alerting call is in alerting state
  • active call is active
  • hungup call had hung up

Voice functions:

  • array nb_voice_endpoint_list (void) / struct nb_voice_endpoint_get (endpoint)
  • Unordered List Itemarray nb_voice_call_list (void) / struct nb_voice_call_get (call)
  • int nb_voice_call_dial (call)
  • int nb_voice_call_accept (call)
  • int nb_voice_call_route (call, endpoint)
  • int nb_voice_call_hangup (call)
  • int nb_voice_call_volume (endpoint, int level)

How to make a call

Start Call

  • Unordered List Itemnb_voice_call_dial(call) or wait for call

Event magement

  • Unordered List ItemOutgoing – do nothing
  • Incomming - nb_voice_call_route(call, target endpoint)
  • Dispatched: alerting → nb_voice_call_accept(call)

End Call