Nokia Telecommunications Oy

Jukka-Pekka Saunamäki

Heikki Juhani Einola

Pekka Pessi

Marko Juhani Suoknuuti

Juha Matti Pirkola

Tero Koskivirta

Aki Petteri Mikkonen

According to an embodiment of the present invention, a system is provided that includes a cellular network, a Public Switched Telephone Network (PSTN) and a mobile IP-telephony network (MIPTN). Both the cellular network and the MIPTN include a Home Function and one or more visited Functions. MIPTN subscribers can roam within the MIPTN. Also, a Gateway Function interfaces the PSTN and the MIPTN to allow roaming between the cellular network and the MIPTN. The Gateway Function performs a dynamic mapping function between PSTN/cellular addresses (e.g., in E.164 format) and MIPTN addresses (e.g., IP addresses) to allow registration and call delivery for subscribers roaming between the cellular network and the MIPTN. A similar type of Gateway Function also allows Short Message Service (SMS) messages to be delivered over the MIPTN as well.

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Espoo, Finland

Jukka-Pekka Saunamäki