When an IP phone is activated to perform a Call Forward All to an outside number (cellular number), any call coming from the PSTN to that phone, hears dial-tone for about 5 seconds, then fast busy.
If a call from another IP Phone on the network calls that same phone that is in a Call Forward All state, it will ring out to the PSTN and call the cellular number which is programmed.
Has anyone ever seen this? Why is this happening?
I've checked the CFwdAll CSS and it is fine.
Again, this only happens when a phone from the PSTN (such as cell) calls into an IP Phone that is in a CFwdAll state to an outside number. The caller hears a dial-tone and then fast busy.
Note, when running a debug isdn q931 on the gateway, it actullay shows the call connecting, but still it does not work.
We have seen this several times, this is called hairpinning,
can you please specify the type of GW and pase debug isdn q931 and debug voice ccapi, to start
CUCM detailed traces will be needed.
The voice gateway is a 2811 ISR, running the H323 protocol. It is connected to the UCMs over a site-to-site VPN tunnel. Attached are the debugs you requested.
Any thoughts on this? Anyone?