In its efforts to move in further on the mobile communications market, NEC UK has brought out a modem for its 11a car phone, to run on Cellnet and Vodafone cellular networks. The cellular modem is one of three modems just launched by NEC, the other two are for use with portable computers. NEC already has 25% of the mobile communications market through its portable handsets and fixed car phones. And it is hoping to increase this share with ProLink CDLC, the cellular modem. CDLC stands for Cellular Data Link Control, an error correction protocol designed by the Racal Electronics group in 1984. Racal Vodata is providing conversion services from the CDLC protocol into X25, public switched telephone and private data network protocols, so that fixed modems at the other end can receieve the signal. V25bis, the autodial/answer protocol is also used by the modem. Racal and NEC say that CDLC guarantees error-free transmissions and a steady transmission rate. NEC is bundling the modems with either an NEC 11 series car phone or in the case of the ProLink MNP and the ProLink Fax, with the NEC Prospeed personal computer. ProLink MNP uses MNP error correction protocols up to MNP5. It is designed as a general purpose modem, for sending and receiving data worldwide. ProLink Fax works as a medium speed modem (2,400 bits per second) or as a facsimile unit for use with Group III faxes. All three modems transmit data at a speed of 2,400bps. The personal computer facsimile units will work with any IBM compatible machine, but ProLink CDLC works only the NEC 11 cab phones and a limited number of other manufacturers' car phones. NEC is also researching personal computers with built-in modems.