The Acterna HST-3000 is a powerful and versatile test instrument for testing ISDN PRI service. Hand-held, rugged and easy-to-use, the HST-3000 is ideal for field use. Its modular design provides a scalable, all-in-one solution for ISDN testing, as well as thorough testing of the facilities over which it is provided. The HST-3000 ISDN PRI option enables testing of Primary Rate ISDN circuits at both the customer site and central office. It supports call placement, receipt, D-Channel Decode analysis for 23B+D, NFAS (Non-Facility Associated Signaling), 24B and backup D channel switching. With the full range of T1 loopcodes and BERT patterns it can also test BER across any combination of channels to verify service before delivery to the customer.