depending on the context, and your userbase, it's usually not too much extra work for them to choose one of 7 carriers and saves you a database lookup & maintenance.
if you insist on keeping the huge database (around 30MB), i actually wrote a miner script a couple years ago to scrape the NPA-NXX data as a CSV from 2 different sources [1]. (you'll have to change the $src key and run it twice)
not sure I understand this. You can lookup which carrier a user uses based on area code and next three digits? what if user ports their number from one carrier to another?
if you insist on keeping the huge database (around 30MB), i actually wrote a miner script a couple years ago to scrape the NPA-NXX data as a CSV from 2 different sources [1]. (you'll have to change the $src key and run it twice)
[1] https://github.com/leeoniya/npa-nxx-miner.php