I captured a Log:
101 is the ringing group. 299, 180, 185 are extensions.
Time Function Message
15:25:20.900 Call::Terminate [CM503008]: Call(129): Call is terminated
15:25:20.779 LineCfg::getInboundTarget [CM503012]: Inbound office hours' rule for LN:10002 forwards to DN:101
15:25:20.639 LineCfg::getInboundTarget [CM503012]: Inbound office hours' rule for LN:10002 forwards to DN:101
15:25:20.629 Call::RouteFailed [CM503015]: Call(129): Attempt to reach [sip:
[email protected]:5060] failed. Reason: No Answer
15:25:05.177 Extension:

rintEndpointInfo [CM505001]: Ext.299: Device info: Device Identified: [Man: 3CX Ltd.;Mod: 3CX VoIP Client;Rev: 1] Capabilities:[reinvite, replaces, able-no-sdp, recvonly] UserAgent: [3CX Phone v5.1] Transport: [sip:192.168.0.243:5060]
15:25:05.177 CallCtrl:

nAnsweredCall [CM503002]: Call(129): Alerting sip:
[email protected]:5070;rinstance=03220560b717135f
15:25:04.596 MediaServerReporting::SetRemoteParty [MS210002] C:129.4:Offer provided. Connection(transcoding mode): 192.168.0.243:7114(7115)
15:25:04.456 MediaServerReporting::SetRemoteParty [MS210002] C:129.3:Offer provided. Connection(transcoding mode): 192.168.0.243:7112(7113)
15:25:04.376 MediaServerReporting::SetRemoteParty [MS210002] C:129.2:Offer provided. Connection(transcoding mode): 127.0.0.1:7110(7111)
15:25:04.156 CallCtrl:

nSelectRouteReq [CM503004]: Call(129): Calling: RingAll101:299Ext.299180Ext.180185Ext.185280285Ext.285@[Dev:sip:
[email protected]:5070;rinstance=03220560b717135f, Dev:sip:
[email protected]:5061, Dev:sip:
[email protected]:5060]
15:25:04.105 MediaServerReporting::SetRemoteParty [MS210000] C:129.1:Offer received. RTP connection: 192.138.136.228:10022(10023)
15:25:04.105 CallCtrl:

nSelectRouteReq [CM503010]: Making route(s) to [sip:
[email protected]:5060]
15:25:04.045 CallLeg::setRemoteSdp Remote SDP is set for legC:129.1
15:25:04.045 Line:

rintEndpointInfo [CM505003]: Provider:[ip_04441550077] Device info: Device Not Identified: User Agent not matched; Capabilities:[reinvite, replaces, able-no-sdp, recvonly] UserAgent: [] Transport: [sip:192.168.0.243:5060]
15:25:04.045 LineCfg::getInboundTarget [CM503012]: Inbound office hours' rule for LN:10002 forwards to DN:101
15:25:03.925 CallCtrl:

nIncomingCall [CM503001]: Call(129): Incoming call from 380555xxxx@(Ln.10002@ip_04441550077) to [sip:
[email protected]:5060]
15:25:03.515 LineCfg::getInboundTarget [CM503012]: Inbound office hours' rule for LN:10002 forwards to DN:101
15:25:03.424 CallLeg:

nNewCall [CM500002]: Info on incoming INVITE:
INVITE sip:
[email protected]:5060;rinstance=4c26b46e20055a6f SIP/2.0
Via: SIP/2.0/UDP 192.138.136.227;branch=z9hG4bK997e.519f2fc3.0
Via: SIP/2.0/UDP 192.138.136.226:5062;branch=z9hG4bK-d87543-c2c5665d3c59353f-1--d87543-;rport=5062
Max-Forwards: 16
Record-Route: [sip:192.138.136.227;ftag=67dc0601;lr=on]
Contact: [sip:
[email protected]:5060]
To: "04441550077"[sip:
[email protected]]
From: "380555xxxx"[sip:
[email protected]:5060];tag=67dc0601
Call-ID: 837bc1249943cb0c@YzA.
CSeq: 1 INVITE
Session-Expires: 100
Min-SE: 90
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE
Supported: timer
Content-Length: 0