ciated Signaling (NFAS)-the ability for one D channel to provide signaling services for multiple PRIs. NFAS allows a customer with multiple PRI connections (typically 11, maximum) to allocate only one D channel to handle signaling for all of them. Each additional PRI, after the first, has 24 B channels. The third iteration of National ISDN was NI-95. NI-95 improved PRI and defined how ISDN is used for access to personal communications services (PCS) networks. NI-96 listed new ISDN features and capabilities and gave references to Bellcore requirements documents for these services. Current information on National ISDN is available at www.nationalisdncouncil.com In May 1996, the U.S.'s largest LECs, under the aegis of the National ISDN Council (Gaithersburg, Maryland), agreed to implement a standard procedure for a customer's establishment of ISDN service. These companies included all regional Bell companies, Cincinnati Bell Telephone Co., GTE Corporation, and Southern New England Telephone Co. The ISDN ordering standard includes codes, known as EZ- ISDN codes, which cover the two most commonly ordered ISDN BRI configurations. Neither of the two EZ ISDN versions (EZ ISDN 1 and EZ ISDN 1a) are aimed at easing the ordering process for videoconferencing configurations (two circuit switched B channels configured for voice/data and a single packet-switched D channel). The standard also includes a uniform SPID format. Under the new definition, a SPID is exactly fourteen digits in length whereas, in the past, SPIDs could be anywhere from 11 to 20 digits. The video codec connects to the station side of the PBX with a BRI connection. Only a handful of switches offer a National ISDN-1 (NI-1) BRI interface (two that do are the NEC ICS and the Northern Telecom Meridian with Release 18 or newer software). Most switches require some type of adapter to be plugged into their regular digital Circuit-switched Networks station ports to support NI-1 connections. At any rate, the videoconferencing equipment, when placed behind a PBX, is