Abstract: A telecommunications system uses an external application gateway (EAG) in communication with a network call control element and external server systems for controlling calls. The telecommunications system further includes a session initiation protocol (SIP) proxy, an intelligent application proxy, and an intelligent application call control. The EAG communicates with a network call control element of a packet network and a third party application server for controlling calls. The external application gateway controls the flow of information between the network call control element and the third party application server, performing such functions as modifying or stripping out network-proprietary information with delivery of the modified messages to the third party application server, keeping track of call state information and associating messages with specific calls, verifying that the third party application server is making only allowed requests, and limiting traffic volumes.