"The best business telephones in the world."

Hi,

I just purchased a new Snom 821. I've got 3 sip accounts that I have been using for over 3 years without any problems with my old Grandstream Phone and my Android phone.

My sipgate.de and fairytel.at accounts work just fine.

But my dialnow.com account is giving me a headake.

Registration works just fine, but I can't make a call.

The only difference that I've found is that the dialnow registrar replies with a 401 instead of a 407 (sipgate/fairytel) authentication challenge to the INVITE. The phone resends the invite a few times, but does not recieve an answer from the server.

I'm behind a NAT, so I tried using a stun server, although I never had to use one with my old phone, but that did not help either.

I'm using Firmware Version snom821-SIP 8.7.5.35. Attached is the SIP Trace and the Log (with the usernames and phone numbers redacted).

Any help would be greatly appreciated! Thanks,

Martin

I just found the answer to my problem here: http://www.ip-phone-forum.de/showthread.php?t=226627

Just disable RTP Encryption and everything works fine!