Facetime verification code doesn't pop up

I would like to use my cellphone number for facetime. I am from Bangladesh. My number is a MNP (mobile number portability). that means the SIM is from another network (Banglalink) but the network is from different one (Robi Axiata). While adding my cellphone number to facetime, i cant receive the verification code sent to my number due its portability. Please help me out of it.