Since mobile telephony has been expanding faster than landline use , new area codes typically have a disproportionately large fraction of mobile and nomadic numbers .
Landline and other services rapidly follow and local network portability can blur these distinctions .
Since mobile telephony has been expanding faster than landline use , new area codes typically have a disproportionately large fraction of mobile and nomadic numbers , although landline and other services rapidly follow and local network portability can blur these distinctions .