GSM This topic has 1 reply, 1 voice, and was last updated 9 years, 5 months ago by E. Viewing 2 posts - 1 through 2 (of 2 total) Author Posts 7th July 2013 at 05:31 #69131 Time slot types in GSMGuest What are the timeslot types used in GSM (eg; TCH, SDD, SDC, SDH, BCH, etc.). I m using Alcatel-Lucent solutions. 7th July 2013 at 08:25 #69132 EGuest Those are called logical channels: TCH is used for voice. SACCH, FACCH, BCCH, and PCH are used for signalling and controle. RACH is used for channel access. SCH is used for synchronization. A logical channel occupies a certain timeslot on a certain transmission frequency. Author Posts Viewing 2 posts - 1 through 2 (of 2 total) The forum ‘Telecom Design’ is closed to new topics and replies.