ITU-T Recommendation Q.50 (07/2001), Signalling between Circuit Multiplication Equipment (CME) and International Switching Centres (ISC) In clause B.2 "Physical level of interface", correct the third paragraph as follows: Since the connected ISC has only 2 Mbit/s interfaces, Time Slot (TS) 16 of these 2 Mbit/s PCM-systems is used in the manner described in 3.3.3.2.25.1.3.2.2/G.704. (In principle, any other physical interface with 2 × 2 bits is suitable for the forward and backward directions.)