Patent ID: 9042378
Filing Date: 2015-05-26
Classification: H04L

Abstract:
1. A method comprising: receiving, by a gateway control function of a gateway device, a session initiation protocol invite message for a first media composition from a second network domain which supports downgrading of media compositions; initiating, by the gateway control function of the gateway device, establishment of a first session with the first media composition in a first leg of a first network domain by transmitting a first call set-up request for said first media composition to said first network domain in response to the receipt of said session initiation protocol invite message for said first media composition at the gateway control function from the second network domain which supports downgrading of media compositions; identifying, by said gateway control function, in response to a rejection message from said first network domain indicating that said first call set-up request for said first media composition in said first leg is rejected by said first network domain; in response to the identifying, releasing said first session and setting up a second session, wherein an active call state of the first leg is maintained at the gateway device during setting up the second session with said first media composition downgraded to have one or more media components removed in said first network domain by said gateway control function by transmitting a second call set-up request from said gateway function to said first network domain via said first leg; and updating, by the gateway control function, a second leg of said second network domain to match said second session with said downgraded media composition being established.