I have an OBi 110 attached to my 3cx server to provide a PBX connection. This worked fine until I upgraded to v15. The closest I have got to it working is I installed a clean v14 server, setup the OBi, did a backup and then created a clean v15 install, using the v14 backup to setup. With this install I can phone out (set to use a 9 followed by the number) but incoming calls give an authentication failure in the activity log, despite the fact the OBi 100 is registered in the 3cx server. I have tried experimenting with settings at both ends and with incoming rules in 3cx but nothing makes any difference.