We have a customer that we setup a 3CX based phone system for. They requested that we set it up so that they could access their extensions on their mobile phones, or setup unique extensions for users in the field on their phones. We have been testing with a single user. We sent her the same configuration file that she has as her phone in office. Everything works when they are out in the field. The problem occurs when they are in the office. If they are on the same LAN as the phone system, the app fails to register I have validated that the wireless she connects to is not getting filtered by a firewall and is on the same layer 2 network. They are currently on 3CX version 14. She is using an Android based phone. Thoughts?