Patent ID: 7860102

Claim:
A method, comprising: controlling an establishment of a call from a calling party located in a first communication network environment to a receiving party located in a second network environment; determining whether information on media parameters supported by the calling party is received in an initialization message for the call, and in an instance in which the information on media parameters supported by the calling party is not received: causing sending, by a network control element, of a specific message based on a service change and fallback function to the receiving party, the specific message including an indication of a primary service and a less preferred service for a call mode used to establish the call; receiving a response to the specific message based on the service change and fallback function from the receiving party, the response comprising information on media parameters supported by the receiving party to the network control element; processing, by the network control element, the information on media parameters supported by the receiving party; and assisting in completing the establishment of the call; wherein the method further comprises selecting a predetermined call mode to establish the call in an instance in which the receiving party is not able to support the service change and the fallback function.