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Callmanager/Skinny Phone H.323 interop issue regarding RTP Source Port

Hi,

We observed the following problem:

When makeing calls between a Skinny phone at the Call Manager and a H.323 gateway, the phone accepts RTP data only if it is sent with with a source port beeing the receive port of the gateway. According to H.323 it should accept the RTP regardless of the source port.

Is this a known issue? Will it be fixed?

Regards

Guntram

PS

Of course we solved the problem on the gateway side, but it should be solved on the call manager side.

2 REPLIES
Silver

Re: Callmanager/Skinny Phone H.323 interop issue regarding RTP S

As per the specification, the ports that are negotiated during H.245 stage would be used for RTP communication. It is not needed that source and destination port are same. All Cisco products (Callmanager and gateways) adhere to the specification. Please check if you have any firewall configured in your network that may impose any restriction on the rtp communication.

New Member

Re: Callmanager/Skinny Phone H.323 interop issue regarding RTP S

Hallo,

this is not the problem.

The problem is with H.245 the ports where RTP is sent TO are exchanged. Of course these ports may be different on both sides. So lets say the CM receives RTP on port 16000 and the Gateway on 17000. But when the gateway sends RTP to 16000 but as source port not 17000 but lets say 5004 the CM ignors the RTP and this is clearly not according to the standard.

Guntram

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