Hii,
E1 is the interface between BTS and BSC.Otherwise known as Abis Interface.1 E1 has 32 time slot. Among which 1st timeslot is for Synchronization and the second time slot is for signaling.That means in 1 E1 we can give 30 telephone connections. The data rate of E1 is 2.048mb and data rate of 1 time slot is 64kbps.
Regards,
Sambit Mohanty