NPA-NXX - 909-378

This is the 909-378 subcode (NPA-NXX) prefix page. Follow a prefix to find the number you are looking for. We divide our pages up to make them more user friendly to navigate!

1. Area Codes
2. 909
3. 909-378

The 909-378 subcode mainly covers Diamond Bar in Los Angeles county. But other numbers maybe included as well.

We have a database of information derived from the public phone records of California state. Many of the numbers in this subcode are Regular Landline registered to Verizon Business. We hear they employ a large number of people in the California office.
Recently there have been an increase in reported calls, we've had over 9818605 comments across our systems for the 909-378 subcode.