How are Calls joined together in JoinType.DIRECT mode?
When the application joins to Call together, there are different permutations of underlying signaling message sequences based on the Calls' states and roles (UAC or UAS).
The relevant Call's states are defined below, based on the SIP implementation in Moho.
- Initialized: The Call is initialized but neither invited or inviting. The Call must be in INITIALIZED state. This applies to Outbound Call only.
- Unanswered: The Call is invited or inviting but no final response has been sent or received. The Call must in one of the INVITING, PROGRESSING, PROGRESSED, and RINGING states.
- Answered: The Call has fully connected with 2XX answer and ACK'ed. The Call must be in ANSWERED state.
The following table shows the supported permutations when two Inbound Call (UAS) are joined.
| Inbound Call (UAS) | Inbound Call (UAS) | SIP Sequence |
| Unanswered | Unanswered |  |
| Answered | Unanswered |  |
| Answered | Answered |  |
The following table shows the supported permutations when an Inbound Call (UAS) is joined with an Outbound Call (UAC).
| Inbound Call (UAS) | Outbound Call (UAC) | SIP Sequence |
| Unanswered | Initialized |  |
| Unanswered | Unanswered | 5 |
| Answered | Initialized | 3 |
| Answered | Answered |  |
The following table shows the supported permutations when two Outbound Calls are joined.
| Outbound Call (UAC) | Outbound Call (UAC) | SIP Sequence |
| Initialized | Initialized | 10 |
| Initialized | Answered | 9 |
| Answered | Answered | 4 |