The invention relates to a remote heterogeneous network mobile real-time communication method. At present, the original phone number of a user cannot be called through Internet voice service. According to the method of the invention, a communication call from a user terminal is transferred to a heterogeneous network through a smart device, and heterogeneous network users can communicate with each other in real time in a seamless manner. A roaming user inserts a mobile phone SIM card or a fixed telephone line into a smart device, and downloads a user mobile application. During international roaming, the mobile phone SIM card of the user is connected with the mobile communication network of a domestic operator through the smart device or the fixed telephone line of the user is connected with a PSTN communication network of a domestic operator, then, the mobile phone SIM card or the fixed telephone line of the user is connected to the Internet of an international roaming place through interactive transmission between the user and a remote heterogeneous network mobile real-time communication system center platform, and finally, response is received at a roaming user terminal. In the global roaming process, an international roaming call can be received or made through the original mobile phone number or fixed telephone number, and the experience is the same as the original mobile phone.