Patent ID: 7739196

Claim:
A method comprising: receiving, by a first session initiation protocol (SIP) server, a first SIP message based on a first party device initiating a call transfer relating to a second party and a third party; retrieving first party call policy information and third party call policy information from a call policy information database; verifying, by the first SIP server using the first party call policy information and the third party call policy information, that the first party is authorized to initiate the call transfer to the third party; creating, by the first SIP server and based on the verifying, a digital signature identifying the first SIP server; generating, by the first SIP server and using account information in the stored profile for the first party, billing information related to the call transfer; appending, by the first SIP server, the billing information and the digital signature to the first SIP message; authenticating, by a processor, the first SIP server based on the digital signature appended to the first SIP message; and completing, by the processor, the call transfer based on the authenticating the first SIP server, and determining whether to bill the first party, with respect to the completed call transfer, based on the billing information appended to the first SIP message.