I am running the trial version of 3CX hosted pbx considering to buy for my organization. I have been trying to register my SIP account to the 3CX server manager many times but I can't. The log shows ; Call or Registration to CAT has failed. sip:+email@example.com:5060 replied: 504 Server Time-out - DNS Problem; from IP:184.108.40.206:5060 or with some setting ; Call or Registration to CAT has failed. sip:+firstname.lastname@example.org:5060 replied: 482 Loop Detected; from IP:220.127.116.11:5060 while I can normally register in other app e.g. zoiper and some other app with the same setting - see log and setting picture; 2016-05-24 13:12:03: Account [email@example.com]'+firstname.lastname@example.org[/email]' registered (SIP), new voice messages: 0, old voice messages: 0. Please anyone give me a clue to go through this. Thank you very much.