Area code 671: Guam
What is area code 671?
Area code 671 is a US territory area code for Guam, on Chamorro Standard Time. All 95 of its prefixes in service are in the Agana rate center. NANPA lists no overlay code for it. Local calls there take 10 digits. The code never shows a line is in service.
Free, runs in your browser; nothing is sent. The sample is a sample, not a real line.
Paste your 671 numbers (a mixed list is fine). They are counted here at once; the free checker then gives every number its E.164 form, country and line type, with a file to download.
By continuing you agree to our Terms and Privacy Policy.
Need the current carrier and real line type of each number?
See the phone add-onArea code 671 facts
| Location | Guam, United States |
|---|---|
| Time zone | Chamorro Standard Time |
| Overlays | None |
| In service since | July 1, 1997 |
| Local calls | 10 digits; toll calls 1 + 10 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
In short: 671 is Guam (Chamorro Standard Time). Format checks here are free and run in your browser; the current carrier and line type need a live lookup. Bulk phone number validator · Pro + Phone plan
Local time in area code 671
Pacific/Guam
Prefixes in service
95 of 792 possible
1 rate center
Which cities and towns use area code 671?
NANPA records each prefix against a rate center, the local billing area a number belongs to, usually named after its main town. These are the 671 rate centers with the most prefixes in service.
| Rate center | Prefixes |
|---|---|
| Agana | 95 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 671 number?
NANPA's dialling plan for 671: local calls inside the code take 10 digits, toll calls 1 + 10 digits. From another area code, dial 1 first. From abroad, use +1. The examples use 555-0147, from a range reserved for fictional numbers.
| Local call inside 671 | 671-555-0147 |
|---|---|
| From another US or Canadian area code | 1-671-555-0147 |
| From outside North America | +1 671 555 0147 |
| E.164, for CRMs and SMS tools | +16715550147 |
When did area code 671 start?
Area code 671 went into service on July 1, 1997. It has no overlay, so every number in its area still starts with it.
Tools for 671 numbers
- Bulk phone number validator
Format, country and number type for every number in a CSV, with E.164 output.
- Area code lookup
Look up any code or a whole list of numbers, or find the codes for a state or city.
- Area code time zone
Local time for a list of numbers, with a callable-now flag.
- NPA-NXX lookup
Rate center and state for one prefix, a level below the area code.
- TCPA calling hours checker
Whether it's inside the federal 8 a.m. to 9 p.m. calling window there now.
Next step
A 671 number tells you where it was issued, not what it is now.
Mobiles, landlines and VoIP lines share area codes, and numbers move between carriers. A live line-type and carrier lookup on every number in your list says which is which, and that decides which calling and texting rules apply. It's in the phone add-on.
No list right now? This tool stays free, no account, so bookmark it for next time. Ctrl+D (⌘+D on a Mac)
Ready to verify now? See the phone add-on
Area code 671 questions
- What state or territory is area code 671?
- Area code 671 is in Guam, United States. Its largest rate centers by number of prefixes are Agana.
- What time zone is area code 671 in?
- Chamorro Standard Time.
- Does area code 671 have an overlay?
- Not as of NANPA's file dated 10/16/2026. Every number in its area uses 671.
- When did area code 671 start?
- Area code 671 went into service on July 1, 1997.
- Is a 671 number a cell phone or a landline?
- The area code can't tell you. In the US and Canada mobiles, landlines and VoIP lines share area codes and prefixes, and numbers move between carriers and line types. Only a live line-type lookup answers it for one number.
- How many phone numbers does area code 671 have?
- 95 of its 792 possible prefixes are in service, and each prefix holds up to 10,000 numbers. That counts prefixes assigned to carriers, not numbers in use.
- Does a valid format mean a 671 number is in service?
- No. A format check only says the digits fit the North American Numbering Plan and that 671 is an assigned code. It cannot tell whether the number is connected, who answers it or which carrier serves it today, because numbers are reassigned and ported. A live carrier lookup reports the current carrier and line type, but even that is not proof someone answers.
- Can I check a list of 671 numbers for free?
- Yes. Paste them in the list tab above or upload a CSV to the bulk phone number validator: format, E.164, country and the numbering-plan line type are free for every row, with no account. Live carrier and line-type lookups come with Pro + Phone at $49.99/mo (5,000 a month).
More area codes
671 is the only area code in Guam. Browse every area code by state and province on the area code index.
Sources
Location, overlays, in-service date and dialling plan: NANPA NPA database, file dated 10/16/2026. Prefixes and rate centers: NANPA central office code assignments, 10/17/2026. Time zones mapped to the IANA time zone database. By the SimpleVerifier Team; how we build these pages.