"Out of service area"

Hello, currently I upgraded my phone and I have come face to face with quite a large issue.My phone is unable to make a connection even though my phone uses the same towers as the rest of my family member, but my phone is not able to make any connection in areas where my family is able to make a connection.I heard i should come here to hopefully be contacted by a straight talk worker who may assist me in this endeavour. Thank you 
