... Pocket Guide for Fundamentals and GSM Testing Publisher: Wandel & Goltermann GmbH & Co Elektronische Meûtechnik P O Box 12 62 ... were added later: GSM1 800 (also DCS1800) and GSM1 900 (also PCS 900) Compared to GSM 900, GSM1 800 and GSM1 900 differ primarily in the air interface Besides using another frequency band, they use a ... 8, 16 and 64 kbit/s formats and transport user data, 24 ± Signaling channels: Can be configured in 16, 32, 56 and 64 kbit/s formats and are used for signaling purposes between the BTS and BSC...