RTP being blocked?

[eleviasrl]

Dear all,

I'm fighting with an ASA that is working well except for an issue with an internal VOIP PBX.

Requirement: connection to PBX must be possible to local (2 LANs) and VPN users (IP range 10.0.1.240-10.0.1.249) only but not from outside (Internet) network.

With actual configuration (see attachment), everything works well with local users, but VPN (L2TP/IPsec) users are able to connect (SIP works - I can register and I get ringing) but all audio (RTP) is blocked both ways (VPN users dont'get audio from local users and viceversa).

I'm not sure if this issue is related to NAT (that I think must be disabled for traffic between VPN and local LANs) or to SIP inspection which is not working as expected (I also tried disabling it but nothing changes).

What do you suggest? 

Thank you very much for your help.

Marco

** UPDATE **

See Wireshark capture file

10.0,1.240 is VPN client (bound to ASA)

192.168.80.0/24 is LAN 1 

192.168.81.0/24 is LAN 2 (VOIP)

192.168.80.20 is PBX interface on LAN 1

192.168.81.20 is PBX interface on LAN 2

[Rajan]

Hi Marco,

Its worth taking a wireshark capture from one of the endpoint involved in the VPN call and see the IP address and the RTP ports are not blocked.

HTH

Rajan

[eleviasrl]

Thanks Rajan,

I did the capture, but it is not clear to me what really happens.

Maybe you can help me further... Thank you.

Marco