| 摘要 |
<p>A telecommunications system including a first (home) mobile telecommunications network A, a second (roaming) mobile telecommunications network B and a third (virtual) mobile telecommunications network C. The virtual network C uses the radio access network of network B to establish wireless communications with a mobile telecommunications device. When a mobile telecommunications device with home network in network A is roaming in network B, the home network A instructs the mobile telecommunications device to register with the virtual network C. IP routing servers 29, 29C in networks A and C enable voice over IP calls to be routed between home network A and the mobile telecommunications device through the virtual network C via the Internet 31.</p> |
