Hi Daz,
Here are some more of the logs from the call, it doesn't ring and it just cuts off after about 5 seconds.
2017-12-01 09:15:03.949333 [NOTICE] switch_core.c:1579 Created ip list lan default (allow)
2017-12-01 09:15:03.949333 [NOTICE] switch_utils.c:545 Adding 192.168.42.42/32 (allow) [] to list lan
2017-12-01 09:15:03.949333 [NOTICE] switch_utils.c:545 Adding 10.2.2.0/24 (allow) [] to list lan
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:17:55.829411 [NOTICE] switch_channel.c:1104 New Channel sofia/internal/07986325912@164.39.47.52 [24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd]
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:17:55.829411 [DEBUG] switch_core_state_machine.c:584 (sofia/internal/07986325912@164.39.47.52) Running State Change CS_NEW (Cur 1 Tot 23)
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:17:55.829411 [DEBUG] sofia.c:9873 sofia/internal/07986325912@164.39.47.52 receiving invite from 164.39.47.52:5060 version: 1.6.19 -36-7a77e0b 64bit
2017-12-01 09:17:55.829411 [DEBUG] sofia.c:10044 IP 164.39.47.52 Rejected by acl "domains". Falling back to Digest auth.
2017-12-01 09:17:55.829411 [DEBUG] sofia.c:2334 detaching session 24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd
2017-12-01 09:17:55.829411 [WARNING] sofia_reg.c:1792 SIP auth challenge (INVITE) on sofia profile 'internal' for [+441619746189@51.140.116.220] from ip 164.39.47.52
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:17:55.829411 [DEBUG] switch_core_state_machine.c:603 (sofia/internal/07986325912@164.39.47.52) State NEW
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [WARNING] switch_core_state_machine.c:687 24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd sofia/internal/07986325912@164.39.47.52 Abandoned
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [NOTICE] switch_core_state_machine.c:690 Hangup sofia/internal/07986325912@164.39.47.52 [CS_NEW] [WRONG_CALL_STATE]
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:584 (sofia/internal/07986325912@164.39.47.52) Running State Change CS_HANGUP (Cur 1 Tot 23)
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:850 (sofia/internal/07986325912@164.39.47.52) Callstate Change DOWN -> HANGUP
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:852 (sofia/internal/07986325912@164.39.47.52) State HANGUP
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] mod_sofia.c:438 Channel sofia/internal/07986325912@164.39.47.52 hanging up, cause: WRONG_CALL_STATE
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:60 sofia/internal/07986325912@164.39.47.52 Standard HANGUP, cause: WRONG_CALL_STATE
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:852 (sofia/internal/07986325912@164.39.47.52) State HANGUP going to sleep
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:619 (sofia/internal/07986325912@164.39.47.52) State Change CS_HANGUP -> CS_REPORTING
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:584 (sofia/internal/07986325912@164.39.47.52) Running State Change CS_REPORTING (Cur 1 Tot 23)
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:938 (sofia/internal/07986325912@164.39.47.52) State REPORTING
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:174 sofia/internal/07986325912@164.39.47.52 Standard REPORTING, cause: WRONG_CALL_STATE
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:938 (sofia/internal/07986325912@164.39.47.52) State REPORTING going to sleep
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:610 (sofia/internal/07986325912@164.39.47.52) State Change CS_REPORTING -> CS_DESTROY
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_session.c:1665 Session 23 (sofia/internal/07986325912@164.39.47.52) Locked, Waiting on external entities
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [NOTICE] switch_core_session.c:1683 Session 23 (sofia/internal/07986325912@164.39.47.52) Ended
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [NOTICE] switch_core_session.c:1687 Close Channel sofia/internal/07986325912@164.39.47.52 [CS_DESTROY]
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:741 (sofia/internal/07986325912@164.39.47.52) Running State Change CS_DESTROY (Cur 0 Tot 23)
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:751 (sofia/internal/07986325912@164.39.47.52) State DESTROY
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] mod_sofia.c:343 sofia/internal/07986325912@164.39.47.52 SOFIA DESTROY
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:181 sofia/internal/07986325912@164.39.47.52 Standard DESTROY
24fbc6ff-92f2-4d21-ade4-d4bfbe4e02dd 2017-12-01 09:18:05.869352 [DEBUG] switch_core_state_machine.c:751 (sofia/internal/07986325912@164.39.47.52) State DESTROY going to sleep