Adaptive routing for packet-based calls using a circuit-based call routing infrastructure

A mobile switching center (MSC) for use in a cellular system infrastructure that supports both circuit switching and packet-based routing, comprising:

• controller operatively coupled to a first plurality of cells;
• first interface operatively coupled to two or more circuit trunk groups, at least one of said circuit trunk groups operatively coupled to a second MSC which is operatively coupled to a second plurality of cells, and at least a second one of said circuit trunk groups operatively coupled to a public switched telephone network (PSTN);
• second interface operatively coupled to one or more packet core access trunk groups, said packet core access trunk groups operatively coupled to a packet core network;
• memory for storing a routing table database, said routing table database having entries representing circuit trunk groups and entries for packet core access trunk groups;
• and
• processor for accessing said memory to retrieve a list of candidate trunk groups and for routing call traffic in accordance with an incoming voice call routing bias by:
• checking the trunk type of the call and checking to see if a routing bias for packet trunks or circuit trunks has been specified;
• if the routing bias is ‘packet’ and the list of candidate trunk groups includes packet core access trunks pulling the packet core access trunks to the front of the candidate trunk group list and attempting to establish outgoing voice connection using the prioritized candidate trunk group list;
• if the routing bias is ‘circuit’ and the list of candidate trunk groups includes packet core access trunks, pushing the packet core access trunks to the end of the candidate trunk group list and attempting to establish outgoing voice connection using the prioritized candidate trunk group list;
• and
• if the routing bias is ‘blank’, attempting to establish outgoing voice connection using the candidate trunk group list.

A method for implementing an incoming voice call routing preference in a telecommunication system comprising:

• setting routing bias settings for incoming packet calls and incoming circuit calls for any candidate trunk group lists as per desired call routing preferences;
• selecting one of packet routing and a non-packet routing for call routing, the candidate trunk group lists for individual routing destinations being updated to indicate if packet voice technology is to be used for call delivery, wherein if packet voice technology is preferred, then a packet core access trunk group is added to a front of a respective trunk group list, and wherein if packet voice technology is to be used only if no circuit trunks are available, then packet core access trunk groups are added at an end of the list;
• starting attempt to establish outgoing voice call using candidate trunk group list derived from digit analysis;
• selecting next trunk group from the candidate trunk group list;
• check if end of trunk group list has been reached;
• if the end is reached, call can't be delivered, and proceeding with secondary treatment;
• if the end is not reached, checking if trunk group indicates packet core access;
• if trunk group does not indicate packet core access, attempting call setup using currently selected circuit trunk group;
• checking if a trunk is available;
• if trunk not available, returning to select next trunk group from the candidate trunk group list;
• if trunk is available, proceeding with call delivery using selected circuit trunk group;
• if trunk group does indicate packet core access, attempting call setup using packet core network;
• checking if a network path is available;
• if network path is unavailable, returning to select next trunk group from the candidate trunk group list;
• and
• if network path is available, proceeding with call delivery over the packet core network.