SNR not working properly from extern

[drehstrom]

Hi everybody,

since a few days, we have a problem with our Unified Mobility feature.

When I call an IP-Phone from intern, the call is redirected after a few seconds to the associated mobile phone. Its ringing and I can answer it - everything works fine. But when I call the very same IP-Phone from extern, the mobile is ringing but when I try to answer the call it falls back to the IP-Phone. The call is open on the mobile phone but the caller still isn't connected and the IP-Phone is ringing...

The peculiar thing is, that it used to work and we didn't tamper with any related settings. So any help would be highly appreciated.

Thanks in advance

SG

[drehstrom]

Update:

The same problem occurs if I enable call forwarding. If I get an internal call everything works fine. Any external call leeds to an indefinite loop. If the called person answers the call the line seems to be routed back to the IP-Phone and back again to the forwarded number and so on. The calling site hears the ringing tone all the time.

Seems we have created a loop but we don't know where to look...

[drehstrom]

2nd Update:

The RTM shows an error 503 Service Unavailable. The Call should be forwarded to another mobile phone.

Detailed Sip Message

SIP/2.0 503 Service Unavailable
Via: SIP/2.0/UDP 10.48.5.14:5060;branch=z9hG4bK228663FE7
From: < sip:CallerNumber@IP-CUBE> ;tag=F19964B0-963
To: < sip:CalledNumber@IP-CUCM> ;tag=5229913~9cc0e0ca-21fd-4b5f-8b07-a78bca3bb64d-16892897
Date: Fri, 22 Nov 2019 10:57:20 GMT
Call-ID: B0ED9F70-C4D11EA-A1C49385-54693DAF@IP-CUBE
CSeq: 101 INVITE
Allow-Events: presence
Reason: Q.850;cause=47
Server: Cisco-CUCM12.5
Session-ID: bda243e328c5504284e87c56c1b9e076;remote=82fb7db02e5b569383ac9fa0f726551d
Content-Length: 0

I'm not sure what Q.850;cause=47 means...