On average, these people pay $60 per month on their mobile service plans. Scarborough finds that in Atlanta, in particular, 75% of households have cellphones. Other major US markets with high cellphone penetration include Detroit with 74%, Austin with 72% and Miami/Ft. Lauderdale also with 72%. Meanwhile, markets like Roanoke/Lynchburg, Buffalo and Charleston/Huntington all have cellphone penetration less than 57%.