equency bands as well, depending on the country's standards; the appropriate radio frequency sim- 2G: Digital Cellular Radio ply needs to be engineered on the front end. cdmaOne is full-duplex (i.e., FDD): 1.25MHz for the forward direction, and 1.25MHz for the reverse direction. TIA/EIA IS-95 was first published in July 1993. The following are the key revi- sions to this standard: IS-95A-The IS-95A revision, published in May 1995, is the basis for many of the commercial 2G CDMA systems around the world. IS-95A describes the structure of the wideband 1.25MHz CDMA channels, power control, call processing, handoffs, and registration techniques for system operation. In addition to voice services, many IS-95A operators provide circuit- switched data connections at 14.4Kbps. IS-95B-The IS-95B revision combines IS-95A, ANSI-J-STD-008, and TSB-74 in a single document. The ANSI-J-STD-008 specification, published in 1995, defines a compatibility standard for 1.8GHz to 2.0GHz CDMA PCS systems. TSB-74 describes interaction between IS-95A and CDMA PCS sys- tems that conform to ANSI-J-STD-008. IS-95B adds a data capability of up to 115Kbps; to achieve 115Kbps, up to eight CDMA traffic channels offer- ing 14.4Kbps need to be aggregated. IS-95B also offers improvements in soft handoffs and interfrequency hard handoffs. Many operators that have com- mercialized IS-95B systems offer 64Kbps packet-switched data services in addition to voice services. Due to the data speeds IS-95B is capable of reach- ing, it is categorized as a 2.5G technology. IS-95 HDR (High Data Rate)-IS-95 HDR provides a spectrally efficient 2.4Mbps peak rate in a standard 1.25MHz channel bandwidth for fixed, portable, and mobile applications. Optimized for packet data services, IS-95 HDR incorporates a flexible architecture based on standard IP. IS-95 HDR is an evolution of CDMA technology with identical radio frequency character- istics to cdmaOne and CDMA2000 1X. IS-95 HDR supports e-mail, Web browsing, mobile e-commerce, telematics, and many other applicati