Kolkata has 4 3G operators - BSNL, Reliance, Aircel, Vodafone while West Bengal has 5 3G operators - BSNL, Reliance, Aircel, Airtel, Vodafone.
In Kolkata all operators commercially rolled out 3G services. It is expected Airtel will enter into spectrum shareing & roaming agreement with Vodafone to offer 3G services in Kolkata. Idea Cellular already promised to give a nation-wide 3G roaming, and thus 3G services on pan India basis.
BSNL 3G Coverage (speed upto 3.6/7.2Mbps)
On April 2010 BSNL 3G was present over 44 cities of WB. Source
Telecomtalk