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Canceling an Outgoing Session

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Use the Terminate method to cancel connecting or Alerted sessions. In Session Initiation Protocol (SIP) messaging there is a distinction between an established or connected session; and a session that is connecting or alerted, in other words one that is not accepted yet by the remote endpoint.

  • When terminating a connected session, a BYE is sent to the remote endpoint.
  • When canceling a connecting (or alerted, or outgoing) session, a CANCEL request is sent to the remote endpoint that is then acknowledged by a 200OK. The INVITE transaction then receives a 487 response from the remote endpoint.

Unified Communications Managed API version 1.0 exposes one method, the Terminate method, to terminate both types of sessions - established and not established. See the example in Terminating an Established Session.