The Agilent HP 37900D Signaling Test Set monitors up to four bi-directional signaling links simultaneously. For in-service performance measurements, the dedicated triggers and filters enable the unit to collect the signaling meassages required and to display real-time signaling interactions. The unit is an ideal tool for installing and maintaining fixed and wireless networks. It supports the following protocols: GSM, PCS, IS41, MAP, ITU-T, ETSI, ANSI, Bellcore, AIN, INAP, V5, X.25, ISDN BRI and PRI and national variants