Fast call set-up for multi-mode communication

A method for reducing a call setup time in a network for a call setup to a multi-mode communication unit, the call setup conducted in accordance with a protocol, the method comprising:

• registering a list of contacts for the multi-mode communication unit with a Session Initiation Protocol (SIP) registrar associated with the protocol in the network, the list of contacts including a first priority of a first contact associated with a first mode of operation and a second priority of a second contact associated with a second mode of operation, wherein the first priority is higher than the second priority, the first contact having a first expiration time;
• determining a quality factor associated with the first mode of operation;
• re-registering the list of contacts with the SIP registrar, the list of contacts including the first contact having a reduced expiration time if the quality factor does not satisfy a first predetermined quality threshold;
• re-determining the quality factor associated with the first mode of operation before the expiration of the first expiration time to provide a second quality factor;
• and
• re-registering the list of contacts, wherein the list of contacts including the first contact having an increased expiration time if the second quality factor exceeds a second predetermined quality threshold.

A method for reducing a call setup time in a network for a call setup to a multi-mode communication unit, the call setup conducted in accordance with a protocol, the method comprising:

• registering a list of contacts for the multi-mode communication unit with a Session Initiation Protocol (SIP) registrar associated with the protocol in the network, the list of contacts including a first priority of a first contact associated with a first mode of operation and a second priority of a second contact associated with a second mode of operation, wherein the first priority is higher than the second priority, the first contact having a first expiration time;
• determining a quality factor associated with the first mode of operation;
• and
• re-registering the list of contacts with the SIP registrar, the list of contacts including the first contact having a reduced expiration time if the quality factor does not satisfy a first predetermined quality threshold, wherein the second contact has a second expiration time according to the second mode of operation of the multi-mode communication unit;
• and wherein the list of contacts includes a third contact having a third expiration time longer than the first expiration time and a third priority, where the third priority is lower than the first and the second priority.