Are you using Rport?
Do you use ALG or any SIP helper?
I know I am not using SIP helper and I have to check the settings on the server plus phone for ALG and update.
Did you fixed it after all? It should work almost out of the box, unless you are running iptables tooo strictly.
The phones values for rtp were incorrect. made the change, dailed an extension the hosted-pbx console and it rings. rtp is selected and the phones registered. since this is the free version most of the advance features are turned off until a fee is paid to use them.
Good that you sorted it out!
The other issue were numerous bugs in Asterisk 13.18.5 and one was not allow securedrtp. I've been asked to re-install a full update from 13.18 to 13.19 will update this ticket after I complete some testing.
Perfect, well done!
Thanks but not done yet. Since submitting this question there has 2 full updates to Zoiper5 [have not tested yet] and full upgrades to Asterisk 13.18.5 to 13.19.1. The 13.19.1 just arrived yesterday. Last week it was 13.19.0. I am setup the asterisk environments for logging to get better information. Will update shortly.
Did you manage somehow?