it does not rely on asn 1 encoding in addition the mixture of functional and stimulus protocol concepts in the design of the inventive protocol results in robust functional characteristics and implementation capability using only lightweight endpoints application_number US 76113601 A description fig1 shows a typical h 323 system with h 323 endpoints 1 to 3 and a gatekeeper 4 connected to a lan wan 5 according to a fully routed h 323 model an application server 6 is also connected to the lan wan 5 which uses tapi tsapi or jtapi to control endpoints for telephony applications the simple supplementary services protocol sssp of the present invention is a generic communication scheme between a server entity such as h 323 gatekeeper 4 and an associated endpoint 1 such as a h 323 terminal or between endpoints 1 the sssp provides a method of call signaling and control signaling that can be carried over existing protocols that support u201c user to user u201d like information such as h 323 or isdn the following portions of the disclosure describe an encoding method according to the present invention primitive definition expandability rules and the preferred transport method for sssp this is followed by illustrations of sssp as a feature protocol between h 323 gatekeeper 4 and h 323 endpoint 1 a generalized method of alpha numeric string encoding and dual tone multiple frequency dtmf string encoding for a sssp protocol data unit pdu is provided as set forth below alpha numeric is the preferred method of encoding when used in h 323 systems the dtmf string encoding method is restricted to the traditional dtmf character set as such it allows sssp to be.