The transaction program initiating the full-duplex conversation sends an allocate request to the partner transaction program. The local conversation then enters SEND/RECEIVE state. The partner receives the FMH-5 and also enters SEND/RECEIVE state. Either side of a full-duplex conversation in SEND/RECEIVE state can receive information.

If the partner transaction program does not support full-duplex, the session capability is negotiated to half-duplex. A conversation can still be allocated, but only a half-duplex conversation is allowed on a half-duplex session.