RTP to H323 Gateway on Call Forward

[megaco]

Hi Guys/Gals,

If you use an IP Phone to setup a call forward to a number on the PSTN (say your mobile phone number) and you are running a CM with a H323 (PSTN) gateway at what point is the RTP Stream active and from what points?

I am under the impression the CM will setup an RTP stream to the Gateway and the gateway will then setup a voice path over PSTN using ISDN standards. If this is a correct assumption then the call is active from CM - Gateway and then Gateway - PSTN.

If this is IP - IP phone then the CM is only used for call establishment/tear down etc...

If someone can add some clarity that would be great - thanks in advance!


I work for myself - my website is

http://www.call.uk.net

 

[ADB100]

CCM informs the Gateway via H.323 where the RTP stream is coming from plus the port numbers etc, this is the same for SCCP between CCM and the IP Phone. I don't believe there is ever an RTP stream between the H.323 gateway and CCM. Once the call is up the signalling remains between the gateway and CCM and between the IP Phone and CCM.
CCM isn't too interested in how the H.323 gateway handles the PSTN site of things, this is different for MGCP where CCM handles the PSTN (ISDN Q.931.QSIG etc) signalling on the routers behalf.

Andy

 

[megaco]

CCM informs the Gateway via H.323 where the RTP stream is coming from.....but this is my question - What if the user has a call forward on the IP Phone - where does the RTP stream come from then? Is their an RTP stream or does the CM signal to the gateway to route the call back out over another voice channel?

Or to clarify on call forwarding is their ever an RTP stream?

I work for myself - my website is

http://www.call.uk.net

 

[ADB100]

OK, I misunderstood (or misread?) your original post. I think(?) there will never actually be an RTP stream in this case. If the H.323 gateway will handle both the incoming and outgoing calls then there will never actually be an RTP stream. The analogue/digital voice will come in one DS0 and go back out another DS0 never actually making it to IP. There will however be lots of H.323 signalling going on. If it was 2 different gateways then it would be an RTP stream between the 2 gateways.

Andy