The 958 and 959 prefixes (NPA-958-XXXX and NPA-959-XXXX) are used as test numbers. 958 numbers are used for most testing, 959 numbers are reserved for inter-exchange carrier testing. 959 numbers can only be reached by being pre-subscribed to that inter-exchange carrier or using an access code (101xxxx-1-NPA-NXX-XXXX). In other words, to dial an AT&T 959-XXXX [...]