Trying to get some SIP trunks to connect to a SIP Trunk provider through a PIX 501 and cannot get the trunks to connect. After running a debug SIP on the PIX I do see the call requests appearing in both directions, however the "from" address displays the internal IP. In theory, the PIX should be replacing the internal IP with the external IP otherwise the SIP provider would deny the call. The provider is setup to only accept calls from a static public IP.
The provider says they support the ingate siparator device to handle SIP connections between the internal/external networks and cannot support PIX/ASA.
Since the PIX is SIP aware I believe it should be able to handle the SIP requests and opening the media ports. I would prefer to keep everything Cisco :) and not introduce more devices into the network.
Can someone please confirm the PIX 501 can handle this and if not, would an upgrade to ASA with v7x support this?