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

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.

Using the router with a SIP phone client.

Endpoints are represented as structs

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

Descriptors

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

States

• 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)

• Unordered List Itemnb_voice_call_dial(call) or wait for call

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

• nb_voice_call_hangup(call)

Sample SDK Script voice call dispatching

Example: Voice Gateway Configuration File