The present invention relates to the telecommunication arts. It finds particular application in conjunction with wireless networks, and it will be described with particular reference thereto. However, it is to be appreciated that the present invention is also amenable to other like applications.
By way of background, wireless telecommunication networks, which are well known, allow mobile devices to communicate with each other and other networks, such as the Internet and the Public Switched Telephone Network (PSTN). For example, the Global System for Mobility (GSM) is a global standard based on TDMA (Time Division Multiple Access). GSM networks deployed in Europe and throughout the world utilize a protocol called the GSM Mobile Application Part (MAP), standardized by the European Telecommunications Standards Institute (ETSI). Other TDMA-based networks and CDMA networks utilize a protocol called ANSI-41, a protocol standardized by the Telecommunications Industry Association (TIA) and the American Standards Institute (ANSI).
When the user of a mobile device is “roaming” in a network other than their own home network, calls are initially routed to a Gateway Mobile Switching Center and then to a Visited Mobile Switching Center. If the mobile user does not answer the call or is busy, then the call is forwarded (called “late” or “conditional” call forwarding)—usually to the mobile user's voicemail system located in the home network. This results in a voice circuit from the home network/Gateway Mobile Switching Center to the Visited Mobile Switching Center and back to the home network voicemail system. This is sometimes called “tromboning the call.” This is especially problematic if this user is roaming internationally, where a tromboned call might traverse much of the globe in two directions. This results in extra costs, use of facilities, and degradation of voice quality, among other things.
The GSM MAP standard, for example, allows MAP messages to be used to optimally route the call, thus eliminating the out and back loop. However, many visited systems in the world do not support late call forwarding optimal routing. Further, the home network service provider who bears the cost for this “tromboned” call has no direct control on the capabilities of the Mobile Switching Centers in the visited network and cannot solve this problem via an upgrade to a system that supports the optimal routing function in the standards.
Accordingly, the present invention contemplates a new and improved method and apparatus that resolves the above-referenced difficulties and others.