Why the my phone is not getting 3g network but when i use 4g sim then network is coming

[Android Central Question]

My phone is nexus 6 why he is not getting 3g network he shows only no service and service provider name in other phone that sim work nicely and one more but when i use 4g sim then in my phone network is coming normely please help

 

[belodion]

Have you spoken to your carrier about it?