EDIT Usage [b]

Note that the Sanskrit 'v' becomes 'b' in Bengali, eg. বিষ্ণু biʂ͟ɳu, Vishnu.

When used in conjuncts, where it is known as bɔ phɔla, it is transcribed as v when the pronounciation is not b:

* when word initial, it is not pronounced:
স্বামী s͟vamī (husband) pronounced ʃamiː
জ্বর j͟vɔr (fever) pronounced ʤɔr

* between vowels, it can lengthen the consonant to which it is attached:
বিশ্ব biʃ͟vô, universe, pronounced biʃːo

* it may also be pronounced as b in conjuncts in words of English origin:
নম্বর nɔm͟bôr, number, pronounced nɔmbor.

See the list of conjuncts with unusual pronounciations.

(The attached picture shows the above examples in case your browser doesn't display the Bengali characters)

 rishida  jsw