Frnk Main, California
(510) 203-XXXX phone validation
Calling or texting numbers that start with 510-203? Check each one first: valid or dead, mobile, landline or VoIP, and the carrier it is on now.
Start 7-day free trial →What the 510-203 prefix tells you, and what it does not
NANPA lists T-Mobile Usa as the company holding the 510-203 block, one of 65 510 prefixes it holds. That is who was given the numbers, not who serves each one today: since number portability, any 510-203 number can move to another carrier and change from landline to mobile or VoIP.
A TrueSearch check returns, for every number:
- ✓Valid or dead. Disconnected and unassigned numbers are flagged before your dialer or SMS tool reaches them.
- ✓Mobile, landline or VoIP. Know which 510-203 numbers can take a text.
- ✓Current carrier. Which may or may not still be T-Mobile Usa.
Upload a list with 510-203 numbers as CSV or Excel. Every number comes back marked valid or dead, mobile, landline or VoIP, with carrier.
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Questions
Which carrier has 510-203 numbers?
The 510-203 block was assigned to T-Mobile Usa according to the NANPA utilized-codes report. Individual numbers can be ported to another carrier, so a live check returns the carrier each number is on today.
Where are 510-203 numbers from?
The 510-203 prefix belongs to the Frnk Main rate center in area code 510 (Oakland, California). People keep their numbers when they move, so this is where the number was first assigned, not where the person is now.
Is a 510-203 number a cell phone?
The prefix alone cannot tell you. Numbers move between mobile, landline and VoIP carriers, so check each number: TrueSearch returns mobile, landline, VoIP or toll-free from live carrier data.
Does TrueSearch check Do Not Call lists?
No. TrueSearch does not check the National Do Not Call Registry, state DNC lists or litigator lists yet. Run those checks separately where they apply.
More 510 prefixes
Area code 510 phone validation
Prefix data: NANPA utilized-codes report. Carrier names belong to their owners; TrueSearch is not affiliated with them. This guide is general information, not legal advice. TrueSearch for Business checks validity, line type and carrier from licensed telecom data. It does not check the National Do Not Call Registry, state DNC lists or the FCC Reassigned Numbers Database. Not a consumer reporting agency; not for FCRA purposes.