Might I suggest Cricket wireless service? Several years ago, I was able to bring my Verizon iPhone 4s to the new carrier. They sent a sim card for $10 and I was good to go. Cricket wireless is a pre-pay with no contracts. We have the $40.00 per month plan, but since it's set up for direct debit on our credit card, they discount each line $5.00. I am not sure what fees (if any) would apply to stop and re-start. They also have a small variety of phones for sale. I recently bought a new iPhone 5s through them for $150.00 plus a new sim card. They offered the new 6/6s models, but I couldn't see spending that much for a phone.
Their coverage is very good and from what I understand, they are owned by AT&T and utilize the same cell towers. Verizon does have better coverage when not near major cities.
You might also check into going pre-paid with Verizon. They too have several plans for a flat rate and you are not obligated to sign up for 2 years.
Henk the German Shepherd & Family
2006 Toyota Sequoia
2015 Jayco Jay Flight 23MB Elite
Previous RV's, 1988 33-foot Class A and 1994 Flagstaff Pop-Up