IP phone cannot process a call after SIP inspection is disabled

[Mady]

Hi Team,

Hope you can help me on this issue. We have Cisco ASA 5505 and we are encountering problem on adding a SIP IP phone. At first, we have problem on registering the phone.Upon disabling the sip inspection on ASA, the IP phone is successfully registered on CUCM but the local IP of phone is registered instead the NAT'd IP on the call manager. Then, that IP phone cannot process a call. 

I just want to know if do I need to have additional config on the firewall side to make the IP phone work properly?

Thank you very much in advance!

[Akshay Rastogi]

Hi Mady,

If you are having NAT for the concerned traffic, then you need to have SIP inspection enabled on the ASA so that the embedded ip can be changed as well.

- Could you please mention the topology on where are CUCM and IP phone with ASA?

- What packets are seen on ASA for registration process when SIP inspection is enabled.

Regards,

Akshay Rastogi

[Mady]

Hi Akshay,

Thank you for your response. Regarding SIP inspection, we cannot register the SIP IP phone when it is enabled. 

The CUCM is located at the Main office and IP phone is in the branch office.

When I packet capture the IP of the phone, I captured none.

Regards,

Mady