The invention discloses a calling method for endpoint across zones in IP network system. The method implements, simply and conveniently, endpoint addressing and calling across GK zones. The method includes: pre-registering an E.164 alias for each endpoint to a gatekeeper managing the endpoint in IP network system, wherein the E.164 alias comprises a gatekeeper zone prefix uniquely indicating the gatekeeper in the IP network system and a unique number indicating the endpoint in its own gatekeeper; a calling endpoint calling a called endpoint with the E.164 alias of the called endpoint.