ISDN is there any different between the DTAG and ITU-T in the S/T - interface. I know that in the U- interface there is a difference with the coding method 4B3T - 2B1Q. I need this information that help me to choose a U and S interface transceivers. Dadi Matza Expand Networks Tel Aviv - "Kiriat Atidim 4" Tel: +972-03-6849480 Fax: +972-03-6489479