Call Transfer by REFER

"Blind" SIP Transfers to new extensions can be accomplished by passing an in-dialog refer between one endpoint and the other. To accomplish this through SIP Witch, the logical uri must be identified as either being local or remote, and if the target being referred to is local, resolved and presented to the target user agent with a request uri that will actually go to a sipwitch target when the user agent turns the refer around. Similarly, a ReferedBy header has to be generated representing the original extension.

SIP Witch cannot perform refer operations for "remote" entities such as many SIP service providers, which do not allow refer or other useful aspects of SIP. When crossing an internodal boundry for an internodal extension, refer uri's must be manipulated so that they are correctly identified and transcribed as local uri's at the destination node.