Viterbi equalizer in a GSM system
Thanks for the answer. You are correct - the training sequence is known by the time you establish any communication.

In case if somebody stumbles upon this in the future, here's how to get this done:

The synchronization burst contains an extended training sequence. It's longer than the regular one and there is only one sequence. You are supposed to use that to equalize, demodulate and decode the SCH burst. Among other useful information, it contains the color code of the BTS, which identifies the training sequence used by that BTS. 

The procedure is nicely explained in this book:

Sajal Kumar Das: "Mobile Handset Design"