Fast call set-up for multi-mode communication

A method for reducing a call setup time 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 with a Session Initiation Protocol (SIP) registrar associated with the protocol, the list of contacts including a first contact having a first expiration time associated with operation according to a first mode of operation of the multi-mode communication unit;
• 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.

An apparatus for reducing a call setup time associated with a call setup in a multi-mode communication environment, the apparatus capable of operating according to a protocol, the apparatus comprising:

• a memory;
• and
• a processor coupled to the memory, the apparatus capable of maintaining at least two contacts in a Session Initiation Protocol (SIP) registrar, the processor configured to:
• assign a first priority to a first contact associated with operation according to a first operational mode and a second priority to a second contact associated with operation according to a second operational mode, wherein the assignment results in the registration of the first contact and the second contact with the SIP registrar with the assigned first priority and the second priority respectively;
• detect an impending switch between the operation according to the first operational mode and the operation according to the second operational mode;
• and
• modify a relative priority between the first priority and the second priority, the modification resulting from one of modifying the first priority and modifying the second priority, such that the first priority of the first contact is not higher than the second priority of the second contact when the impending switch is detected, wherein the modification results in the modification of the first contact and the second contact at the SIP registrar with the modified relative priority.

An apparatus for reducing a call setup time associated with a call setup in a multi-mode communication environment, the apparatus capable of operating according to a protocol, the apparatus comprising:

• a memory;
• and
• a processor coupled to the memory, the processor configured to:
• maintain a contact list in a Session Initiation Protocol (SIP) registrar, the contact list containing at least a first contact associated with operation according to a first operational mode, the first contact having a first priority and a first expiration time, and a second contact associated with operation according to a second operational mode, the second contact having a second priority and a second expiration time, wherein maintaining the contact list results in the registration of the first contact and the second contact with the SIP registrar with the assigned first priority and the second priority respectively;
• determine a quality factor associated with the first operational mode;
• and
• modify the contact list at the SIP registrar if the quality factor does not meet a predetermined quality level, the modification resulting in at least one of:
• a third expiration time for the first contact, the third expiration time being shorter than the first expiration time and shorter than the second expiration time, and
• a third priority for the first contact, the third priority being not higher than the second priority.