Signalling options

The following details can be configured in the Signalling options section of the carrier settings page. They are designed to provide a consistent signalling flow between endpoints.

RTP Proxy

Select one of four settings to determine whether an RTP Proxy will be used for some or all calls to this carrier. You must purchase RTP Proxy channels for this feature to work.

•	Do not proxy: Calls to this carrier will not use an RTP Proxy, although this can be overridden by the calling account's settings.

•	Proxy on NAT: DUAL Softswitch can detect if a caller's device is behind a NAT router. If this state is detected, the audio for the call will pass through an RTP Proxy.

•	Proxy with override: Calls to this carrier will be passed through an RTP Proxy, unless the calling account's proxy setting is "Never proxy".

•	Always proxy: All calls to this carrier will pass through an RTP Proxy channel, regardless of the calling accounts' settings.

Long wait timer

A call to a carrier will fail if that carrier does not respond to that call in a timely manner. A suitable response is a "100" status message for a SIP carrier or a CallProceeding message for an H.323 carrier. If the carrier is part of Least Cost Routing, then this failure will cause Alternative Routing to be invoked.

The length if this timer can be changed between two values using this settings. The two values themselves can be changed by making a request to our support team at support@dualsoftswitch.com

Add Progress

Add a progress indication to the caller when the media is negotiated. This can sometimes cure "double ringing" experienced on carriers with improperly configured equipment.

Ignore Progress

Ignore H.225 Progress messages from the carrier, and wait for an Alerting or Connect. Acting on an unnecessary Progress message can sometimes block Alternative Routing. This setting only applies to H.323 carriers.

Alerting delay

This settings has two different meanings depending on the signalling protocol set for the carrier:

•	H.323 - Ignore Alerting messages from a carrier if it does not include Fast Start. This ensures that ringback tones are sent to a caller if the carrier subsequently sends another Alerting or Progress message.

•	SIP - Ignore "180 Ringing" messages, and wait for "183 Session Progress". This ensures that ringback tones are sent to a caller if a carrier sending both 180 and 183.

Single G.729

Offering multiple G.729 annexes to some carrier equipment can cause calls to fail. This option ensures that only one G.729 annex is offered to this carrier.