| 主权项 |
1. A method of negotiating Media Gateways (MGs) between a plurality of call control nodes (CCNs), the method comprising the steps of:
a first CCN building an MG identifier list, each identifier in the MG identifier list being a Bearer Control Unit Identifier (BCU-ID) having at least one MG capable of being used in a call by the first CCN; sending the MG identifier list to a second CCN; the second CCN removing any identifiers, from the MG identifier list, associated with any MG which cannot be used in the call by the second CCN, thereby forming a modified MG identifier list associated with at least one MG capable of being used in a call by the first CCN and the second CCN; sending the modified MG identifier list to a third CCN; the third CCN removing, from the modified MG identifier list, any identifiers associated with any MG that is not capable of being used in the call by the third CCN, thereby forming a final MG identifier list associated with at least one MG capable of being used in a call by the first CCN, the second CCN, and the third CCN; the third CCN selecting a specified MG from the final MG identifier list for establishing a user plane; sending a first backward message from the third CCN to the second CCN identifying the specified MG; and sending a second backward message from the second CCN to the first CCN identifying the specified MG. |
