Re questions on digital telephony over T1. If you want to look at ISDN as well as ONP products and many countries, the European 3.1 kHz ISDN telephony requirements may also be of interest (i.e. if trying to make a global product). These are based on 64 kbit/s Timeslots.
In simple terms, obtain the European standard From ETSI (possibly on the free www download service) you require standard TBR8. This is used with EC release notes (from the EU official journal) to form CTR 8. ETSI are at www.etsi.fr/ There may be a Bellcore spec for NI-2 ISDN telephony in the USA. For both ONP and ISDN: You should also look at the transmission parameters such as those found in G.series ITU-T. Things like delay, total distortion, gain vs level, Gain / level linearity etc. Some of these factors will affect the design of the Dig phone interface i.e. round trip delays, QDUs, Loss / gain plans. Hope this helps. Bill Ellingford, Approvals Manager Motion Media Technology Ltd
