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In software version 10.5.1, feature F-0759 SIP Refer for Call Transfer was added. This method utilizes the Refer-To: Header field to pass contact information such as URI INFO provided in the request. In software version 10.5.1 ER4 Feature F-1683 Handling URI parameters in the Refer To: header adds to the IMG the ability to transfer any URI Parameters from the Transferor to the Transfer Target. The URI Parameters are passed in the Outgoing INVITE only and is limited to 512 bytes in length. This feature allows customers the ability to transport call control related information (Call Waiting, Call Forward on Busy, etc) from the Transferor to the SIP Transfer Target during a referral scenario.