Demand for wireless multimedia services, such as messaging, data services, and Voice over Internet Protocol (VoIP) is steadily increasing. Many of these new services are transmitted via Internet Protocol (IP), as packetized digital data in the same manner as an Internet transmission. Not all wireless devices, however, may have the capability to accept an IP signal. When a wireless device has the capability, it must have an established IP context to communicate via IP, which is usually accomplished at the wireless terminal user's initiative.
Wireless communication over IP requires a Packet Data Protocol (PDP) context between the wireless terminal and the Serving Global Support Node (SGSN). Once the wireless terminal requests and initiates a PDP context with the SGSN, the SSGN requests an IP address from the Global Gateway Support Node (GGSN). The GGSN then assigns an IP address to the wireless terminal and registers that address. Due to the limited number of IP addresses that are assigned to each wireless provider and the very large number of wireless terminals in existence, each wireless terminal cannot have a permanent IP address.
A problem arises when an IP signal requires delivery to a wireless terminal, because a wireless terminal must request and obtain an IP address. The receiving terminal can not receive the signal without establishing an IP PDP context. It is desirable that wireless terminals have the ability to receive VoIP calls and other IP data transmissions from any number of applications under these circumstances.
Several messaging protocols currently operate on wireless networks and may not be compatible with each other. A signal sent by an application or wireless terminal using a different protocol than the receiving wireless terminal may encounter delivery problems. As a signal enters the network, it is routed through the architecture based on its signal and the wireless terminal to which it is to be delivered. Several layers of decision trees based on the above-stated parameters determine signal routing as a signal propagates through the network. The element or section of the network the signal is routed to may not have the capability to properly deliver the signal. If the signal is not deliverable at the end of a final decision tree, the signal may be dropped with no recourse for later or alternate delivery because no element of the network determines a resolution for such a problem.
One such messaging service that attempts to correct the problem is the IP Multimedia Service (IMS). IMS is based on the IP Multimedia Subsystem, a recent development of all-IP data services in next generation wireless networks. The IMS combines the IP Multimedia Subsystem protocols with several current messaging systems. IMS, however, is not a full solution because it suffers from the same signal and data delivery problems. If the network attempted signal delivery to a device that did not support IMS, it would follow the current network decision structures ending in delivery failure.
Another problem occurs when adding new functions and features to the network. Adding functions and capabilities to the system requires new hardware and layers of software. Much of the current network elements must be reprogrammed to recognize new functions and capabilities. Such steps add layers of processes and decision trees that further complicate signal routing.
An additional problem for wireless providers is billing for VoIP calls. It is possible to place a VoIP call by accessing an Internet Web site and only be charged for wireless Internet access, not for the standard voice call airtime.