If you are trying to get Acrobits SIP phone working on your iPhone with the 3CX VoIP telephone system use the settings indicated below. For the domain entered the local network DNS name of the server i.e. what is used to connect to 3CX on the local network. For Register via leave the default setting.
3CX needs the following ports forwarded to the VOIP server in order to work. The documentation does not by default describe which ones are meant to be TCP and which UDP so here they are: Port 5060 (TCP and UDP) – Used for SIP protocol transmission
Imagine there is a big wall of “pigeon holes” between your computer and the internet. Each pigeon hole is numbered and each hole has specific purpose. For example, we only accept new SMTP mail in pigeon hole number 25. We only accept WWW requests in pigeon hole number 80. We call these pigeon holes, “ports”..
After being hit with a few $700 and $800 excess charges by Telstra, who refuse to do anything about it and provide no warning system (they make more money that way) I was having a hard time figuring out how-