A method for callback processing in telecommunication capability opening, a telecommunication capability opening server, a client, and a telecommunication capability opening service system are disclosed. The method includes: receiving a telecommunication capability application programming interface (API) call request sent by a client, where the telecommunication capability API call request includes a callback information parameter; performing callback processing according to the telecommunication capability API call request, and generating a callback message according to the callback information parameter; and pushing the callback message to the client. The method may also include: initiating a telecommunication capability API call request to a telecommunication capability opening server, where the telecommunication capability API call request includes a callback information parameter; receiving a callback message pushed by the telecommunication capability opening server, and parsing the callback message; and determining, according to a parsing result, a function that callback processing needs, and calling the function.