in to compete with cellular radio systems, where the cordless telephone will operate in microcells. 18.9.2 North American Cordless Telephones The North American cordless telephone operates in the 50-MHz frequency band with 25 frequency pairs using frequency modulation. Their ERP is on the order of 20 uW. Reference 18 suggests that this analog technology will continue for some time into the future because of the telephone's low cost. These may be replaced by some form of the wireless local loop (WLL) operating in the 30- or 40-GHz band. 18.9.3 European Cordless Telephones The first-generation European cordless telephone provided for eight channel pairs near 1.7 MHz (base unit transmit) and 47.5 MHz (handset transmit). Most of these units could only access one or two channel pairs. Some called this "standard" CTO. This was followed by another analog cordless telephone based on a standard known as CEPT/CT1. CT1 has 40 25-kHz duplex channel pairs operating in the bands 914-915 MHz and 959-960 MHz. There is also a CT1+ in the bands 885-887 MHz and 930-932 MHz, which do not overlap the GSM allocation. CT1 is called a coexistence standard (not a compatible standard), such that cordless telephones from different manufacturers do not CELLULAR AND PCS RADIO SYSTEMS interoperate. The present embedded base is about 50 million units with some 15 million units are expected to be sold in 2004. Two digital standards have evolved in Europe: the CT2 Common Air Interface and DECT (digital European cordless telephone). In both standards, speech coding uses ADPCM (adaptive differential PCM). The ADPCM speech and control data are mod- ulated onto a carrier at a rate of 72 kbps using Gaussian-filtered FSK (GFSK) and are transmitted in 2-msec frames. One base-to-handset burst and one handset-to-base burst are included in each frame. The frequency allocation for CT2 consists of 40 FDMA channels with 100-kHz spac- ing in the band 864-868 MHz. The maximum transmit power is 10 mW, and a two-level power control supports prevention of desensi