E1 has 32 timeslots as has been said..
Usually 1 timeslot is allocated for signalling and 1 for synchronization that is why some claims 30 timeslots, some cliimed 31 timeslots.
With regards to call capacity, for E1 each timeslot has 64 kbps and a certain voice call (VC) is encoded with 16 kbps full rate and 8 kbps in half rate mode.
So considering 1 TS in E1, in can carry up to 4 VC at fullrate. With 30 TS a certain E1 can carry as much as 120 calls.(4 VCperTS x 30TS)