Can Not find VoLTE for sims. Is there any firmware or country restrictions?

[mnijhum]

I can not find the enable VOLTE option in my Samsung galaxy a50s.  what to do? Does it vary from firmware to firmware? my mobile operator just launched volte in my area. Other phones like xiaomi got volte in my area. 

[mnijhum]

I am from Bangladesh but my sim supports LTE

[mnijhum]

they just launched it and other mobile phones in my area are getting this service.

[Samsunglovers2004]

service provider name

[mnijhum]

grameenphone and it is volte supported

[mkarthick]

what sims are u using

[mnijhum]

grameenphone and it is VOLTE supported

[Samsunglovers2004]

try it network setting reset

[mnijhum]

how?

[Samsunglovers2004]

setting->genrel setting->reset network setting after not a solve a problem to fectory reset mobile one time