Read it again.
Do not get confused with channel and time slot. Each channel consists of two frequencies, one for TX one for RX.
Each channel is divided into 8 TS.
Here one TS is dedicated to BCCH and one for SDCCH. Remaining 14TS= 14TCH= 8.2Erlang of traffic(from Erlang B table with 2% GoS).
They can handle.8.2/25mEr=320 Subscribers if 25mEr/Subs.is used by operator.
OR 8.2/40mEr=200 Subscribers if 40mEr/Subs is used by operator. OR 14 Subscribers simultaneously.