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Packet Capture on Cisco 881

Level 1
Level 1

Hi All, 


I apologize if I am posting in the wrong category or I decided to word my question wrong.


Basically I have a client that has an old Cisco 881 router. 

They have VOIP from their ISP.


Setup is VOIP Provider > Cable Circuit > Cisco 881 > ATA SPA 122

When a call comes in, it rings busy but Outbound Calls are fine.

The ISP has replaced the ATA SPA 122, but issue still persist.

ISP provided a Packet Capture from their side of the network and it shows that the VOIP Provider is sending INVITES but the 881 isn't sending a response.


So the question becomes is there a debug/packet capture that I can run on the Cisco 881 router to verify if the INVITE from the ISP is actually coming into the 881 and the 881 is forwarding it to ATA? or is there another method I can try?


My key thing on this is that I am wanting to know if the 881 is passing the INVITE to the ATA SPA 122, or if the 881 is just dropping the request.

The 881 itself does not handle VOIP itself, the VOIP just comes into the 881 as a data packet, hits the Voice VLAN and is forwarded to the ATA SPA 122 to be converted however it needs to be converted (mainly digital to analog).

2 Replies 2


Try debug ccsip messages and see where INVITES are received. FYI, they
might be received by dropped by 881 for many reasons but this command is a
good start.

**** please remember to rate useful posts

Thank you. I will be back to work Wednesday, so I will try it then and see where it gets me.

I won't be able to post the results until then.