- City / exchange
- Diamondbar
- Province / state
- California
- Country
- United States
- Carrier
- Onvoy, LLC - CA
- Line type
- Likely VoIP / virtual number
- OCN
- 649C
- Status
- Assigned
- Assigned
- 07/21/2026
- Number pooling
- Yes (block shared between carriers)
840-289 phone numbers
Diamondbar, California, United States · Onvoy, LLC - CA
Reported numbers in 840-289
No numbers in this block have been reported by visitors yet.
What does the 840-289 prefix tell you?
Every North American number is area code + prefix + line. The prefix 840-289 was assigned to Onvoy, LLC - CA on 07/21/2026 for the Diamondbar exchange. A call from this block usually originates from a Onvoy, LLC - CA customer in or near Diamondbar, but caller ID can be spoofed to show any number.