Patent ID: 8515396

Claim:
A method for providing ringback tone presence service, comprising: receiving, by a Mobile Switching Center (MSC), a call request from a calling user terminal; sending, by the MSC, a request for obtaining routing information of a called user terminal to a Home Location Register (HLR), wherein the called user terminal pertains to the HLR, and wherein the called user terminal is a subscriber of a ringback tone presence service based on a called user terminal number; receiving, by the MSC from the HLR, a called roaming number and subscription information of the ringback tone presence service; sending, by the MSC, a calling user terminal number, the called user terminal number, and a ringback tone presence service identifier to a ringback tone server (RBTS) if the called user terminal is in an idle state; sending, by the RBTS, a request for obtaining presence information to a presence server after receiving the ringback tone presence service identifier; sending, by the RBTS, the presence information to the calling user terminal in a format understood by the calling user terminal after the RBTS obtains the presence information of the called user terminal; determining, by the RBTS, whether the sending of the presence information by the RBTS to the calling user terminal is completed after the called user terminal answers; continuing, by the RBTS, to send the presence information to the calling user terminal when it is determined that the RBTS has not completed the sending of the presence information; and establishing a normal signaling link between the calling user terminal and the called user terminal until the presence information has been completely sent to the calling user terminal.