SIP: Transfer - AttendedAliceBobCarolAliceBobCarol[01]INVITE[02]180 Ringing[03]200 OK[04]ACKBoth Way RTPBob places Alice on hold[05]INVITE (sdp: a=sendonly)[06]200 OK (sdp: a=recvonly)[07]ACK.No RTPBob calls Carol to announce transfer[08]INVITE[09]180 Ringing[10]200 OK[11]ACKBoth Way RTPBob places Carol on hold[12]INVITE (sdp: a=sendonly)[13]200 OK (sdp: a=recvonly)[14]ACK.No RTPBob transfers Alice to Carol[15]REFER Refer-To: C[16]202 Accepted[17]NOTIFY 100 TryingSubscription-State: active[18]200 OKAlice establishes session with Carol, which replaces thesession between Bob and Carol[19]INVITE Replaces: B[20]200 OK[21]ACKBoth Way RTP[22]BYE[23]200 OKAlice tells Bob that the call has been successfullytransferred.[24]NOTIFY 200 OKSubscription-State: terminated[25]200 OK[26]BYE[27]200 OKRFC5359: Transfer - Attended