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2.2.1.4 Presence-State Header Field Syntax

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This protocol defines a new Presence-State header field.

The Augmented Backus-Naur Form (ABNF), as defined in [RFC5234], syntax for the Presence-State header field<2> is as follows:

presence-state         = "presence-State" HCOLON presence-state-value
presence-state-value   = register-action[SEMI primary-cluster-state [SEMI user-services-state-unavailable] ]
register-action        = "register-action" EQUAL register-action-value
register-action-value  = ""added"" / ""refreshed"" / ""fixed""
primary-cluster-state  = "primary-cluster-type" EQUAL primary-cluster-type-value SEMI cluster-connection-type-state
primary-cluster-type-value = ""central"" / ""remote""
cluster-connection-type-state = "is-connected-to-primary" EQUAL yes-no-value
yes-no-value = ""yes"" / ""no""
user-services-state-unavailable = "user-services-state=unavailable"

The ABNF syntax for the Presence-State header<3> field is as follows:

presence-state         = "presence-State" HCOLON presence-state-value
presence-state-value   = "register-action"
register-action-value  = ""added"" / ""refreshed"" / ""fixed""

The SIP registrar MAY add at most one Presence-State header field in the 200 response to the REGISTER request.