IMS Conference Call with MRF

📘 What This Shows

Below is a complete IMS Conference Call Flow using MRF, where:

1. UE A and UE B first establish a call.
2. Then UE C joins the ongoing conference.
3. Finally, all parties disconnect together, terminating the session.

This scenario illustrates how conference sessions are dynamically updated in IMS using AS (Application Server) and MRF (MRFC/MRFP).

 

3GPP IMS Conference Call with MRF – Late Joiner and Group Termination

sequenceDiagram participant UE_A as UE A participant UE_B as UE B participant UE_C as UE C participant P_CSCF as P-CSCF participant S_CSCF as S-CSCF participant AS as Conference AS participant MRFC as MRFC (Control) participant MRFP as MRFP (Media) %% Step 1: UE A joins conference UE_A->>P_CSCF: INVITE (Conference URI) P_CSCF->>S_CSCF: INVITE S_CSCF->>AS: INVITE (triggered by iFC) AS->>MRFC: Allocate conference MRFC->>MRFP: Create media mixer MRFP-->>MRFC: 200 OK MRFC-->>AS: 200 OK AS-->>S_CSCF: 200 OK (with SDP) S_CSCF-->>P_CSCF: 200 OK P_CSCF-->>UE_A: 200 OK UE_A->>P_CSCF: ACK P_CSCF->>S_CSCF: ACK S_CSCF->>AS: ACK UE_A-->>MRFP: RTP Media (A joins) %% Step 2: UE B joins same conference UE_B->>P_CSCF: INVITE (Conference URI) P_CSCF->>S_CSCF: INVITE S_CSCF->>AS: INVITE AS->>MRFC: Add UE B to conference MRFC->>MRFP: Update mixer MRFP-->>MRFC: OK MRFC-->>AS: OK AS-->>S_CSCF: 200 OK S_CSCF-->>P_CSCF: 200 OK P_CSCF-->>UE_B: 200 OK UE_B->>P_CSCF: ACK P_CSCF->>S_CSCF: ACK S_CSCF->>AS: ACK UE_B-->>MRFP: RTP Media (B joins) MRFP-->>UE_A: Mixed RTP (A hears B) MRFP-->>UE_B: Mixed RTP (B hears A) %% Step 3: UE C joins later UE_C->>P_CSCF: INVITE (Conference URI) P_CSCF->>S_CSCF: INVITE S_CSCF->>AS: INVITE AS->>MRFC: Add UE C to conference MRFC->>MRFP: Update mixer MRFP-->>MRFC: OK MRFC-->>AS: OK AS-->>S_CSCF: 200 OK S_CSCF-->>P_CSCF: 200 OK P_CSCF-->>UE_C: 200 OK UE_C->>P_CSCF: ACK P_CSCF->>S_CSCF: ACK S_CSCF->>AS: ACK UE_C-->>MRFP: RTP Media (C joins) MRFP-->>UE_A: Mixed RTP (A hears B & C) MRFP-->>UE_B: Mixed RTP (B hears A & C) MRFP-->>UE_C: Mixed RTP (C hears A & B) %% Step 4: All UEs end the call UE_A->>P_CSCF: BYE P_CSCF->>S_CSCF: BYE S_CSCF->>AS: BYE AS->>MRFC: Remove UE A MRFC->>MRFP: Update mixer AS-->>S_CSCF: 200 OK S_CSCF-->>P_CSCF: 200 OK P_CSCF-->>UE_A: 200 OK UE_B->>P_CSCF: BYE P_CSCF->>S_CSCF: BYE S_CSCF->>AS: BYE AS->>MRFC: Remove UE B MRFC->>MRFP: Update mixer AS-->>S_CSCF: 200 OK S_CSCF-->>P_CSCF: 200 OK P_CSCF-->>UE_B: 200 OK UE_C->>P_CSCF: BYE P_CSCF->>S_CSCF: BYE S_CSCF->>AS: BYE AS->>MRFC: Tear down conference MRFC->>MRFP: Release mixer AS-->>S_CSCF: 200 OK S_CSCF-->>P_CSCF: 200 OK P_CSCF-->>UE_C: 200 OK