I have always used 3CX in combination with Rynga, a Betamax provider. however, since July 26th, it won;t register anymore. I get 503 error. 31-07-2012 14:33:20.938 [CM504007]: Next attempt to register Lc:10001(@Rynga[<sip:email@example.com:5060>]) is scheduled in 600 seconds 31-07-2012 14:33:20.876 [CM504005]: Registration failed for: Lc:10001(@Rynga[<sip:firstname.lastname@example.org:5060>]); Cause: Cause: 503 Service Unavailable/REGISTER from local 31-07-2012 14:32:39.579 Registration attempt for Lc:10001(@Rynga[<sip:email@example.com:5060>]) is scheduled in 20 sec. And even after installation of 3CX v11 and a fresh install, I get the same error. My SIP-phone (and 3CX Phone software) can perfectly register with Rynga. What's the problem with 3CX Phone System??