hi,
yes its true that Bangladeshi people are not able to use ip phone. because BTRC do not allow voice over bttb connect. now question is, how the call center will be boomed?
there is other option but for call center ip phone is the best way.
in addition, Bangladeshi people are now much more conscious about IT ever since before. there is a call center forum i have found where people are exchanging their thoughts
best of luck