SMS for NMT networks Since June 1997, the Polish NMT operator Centertel, is operating the first SMSC for the analog NMT networks. According the the (only) vendor of the SMSC for NMT, the Brittish/Dutch company CMG, the SMSC is now in a pilot stage and under real-life tests, it is successful and will commercially available as from September 1, 1997. At a telecom conference in June '97 in Warsaw, visitors could send Short Messages from one NMT phone to another via an SMSC for the first time ever! The phones used were the new Nokia 450 model. How does it work? Unlike in GSM, the Short Messages are not going via the signalling channel in SMS for NMT. The NMT specification group did not want to alter the signalling specifications since this would have to big an impact on exsiting networks, so instead a simple modem connection is used over the voice channel. These NMT SMS modems are the so-called DMS (Data Mobile Station) modems. The disadvantages of this approach is that is is slower than in GSM (the total submission and delivery cycle require an actual call set-up) and, of minor importance, the messages cannot be delivered while one is calling. The advantage is that the message can be delivered via the ordinary telephone lines, which means that the NMT networks do even need to be roaming partners to have an SM delivered (remember: it is just an ordinary phone (data) call!) SMS silent delivery The SMS service for NMT as well as the SMSC do not require any changes to the NMT switches (MTX), which makes it possible to deliver a Short Message to virtually any NMT phone capable of handling SMS. Although, theoretically there is no need to change the software in the MTX's, not doing so means that the receipt of a Short Message will make the phone ring as an ordinary call. The major NMT switch (MTX) vendors, i.e. Nokia and Ericcson, have announced that they will have all MTX software ready even this year, or latest early-1998. Exchanging messages with GSM When the NMT operator is also a GSM operator, e.g. all Scandinavian operators, it is very easy: the SMSC can handle both GSM and NMT at the same time and decides on the destination number whether the message should be delivered to the NMT or to the GSM network. When the NMT operator does not have GSM it is still possible, either by getting a (GSM) SMS roaming agreement (install a signalling link to the SMS roaming partner's GSM network) or by delivering the messages directly to the GSM SMSC. The latter solution does not even require an agreement with the GSM operator, by using the GSM operator's standard PSTN or X.25 access mechanisms for submitting messages. However, a special agreement will most likely be quicker, more reliable, and probably even cheaper. You can E-mail your questions or requests for more info about SMSC for NMT.