Connecticut area codes
Connecticut uses 4 area codes. The oldest is 203, in service since 1947; the newest is 959, from 2014. Across them 2,023 of 3,144 possible number blocks are allocated, 64.3% of capacity. 203 and 860 are at or past 95%, which is why new numbers there come from overlays rather than the original code. AT&T holds 44.9% of the 2,023 assigned blocks across the state, ahead of Verizon at 14.9%; a further 5.4% sits with CLEC and VoIP holders outside the national carriers. In the 33 days to 30 October 2026, FTC complaints named a Connecticut caller ID 1,982 times – 0.9% of all complaints in the window, most often 860 with 755 (120th of 422 nationally). NANPA records 176 rate centers across the state's codes, and local calls take all ten digits.
All 4 codes
| Code | In service | Blocks used | Largest holder | Complaints | Shares area with |
|---|---|---|---|---|---|
| 203 | 1947 | 784/786 | AT&T 55.7% | 537 | 475 |
| 475 | 2009 | 292/786 | Onvoy 22.3% | 442 | 203 |
| 860 | 1995 | 783/786 | AT&T 55.3% | 755 | 959 |
| 959 | 2014 | 164/786 | Other CLEC / VoIP 30.5% | 248 | 860 |
Block share is share of allocated number blocks, not of subscribers. Complaint counts cover 28 Sep – 30 Oct 2026 and reflect spoofed caller IDs as much as real calls.
How full Connecticut’s codes are
A code holds at most 786 blocks of 10,000 numbers each. When a code fills up, the administrator does not reclaim numbers – it adds an overlay, and from then on new numbers in the same area come from the new code.
Full or nearly full
Who holds the number blocks
Counted from every assigned block in the state: 2,023 blocks, each with the holder NANPA recorded for it. Percentages are measured, not estimated.
| Holder | Blocks | Share of Connecticut | Largest in |
|---|---|---|---|
| AT&T | 909 | 44.9% | 2 codes |
| Verizon | 302 | 14.9% | – |
| T-Mobile | 189 | 9.3% | – |
| Onvoy | 135 | 6.7% | 1 code |
| Other CLEC / VoIP | 109 | 5.4% | 1 code |
| Windstream | 94 | 4.6% | – |
| Lumen | 78 | 3.9% | – |
| Bandwidth | 39 | 1.9% | – |
| Comcast | 36 | 1.8% | – |
| Altice | 35 | 1.7% | – |
| Peerless | 30 | 1.5% | – |
| Spok | 22 | 1.1% | – |
“Other CLEC / VoIP” is not one company: it is every holder outside the national carriers counted together, which is what resellers and app-based numbers look like in the records. This is allocation, not subscribers.
Spam complaints naming Connecticut codes
FTC Do Not Call complaints where the caller ID shown was a Connecticut number, 28 Sep – 30 Oct 2026 (33 days). Caller IDs on spam calls are routinely faked, so these are complaints about the code, not calls proven to come from it.
How Connecticut got its codes
1 in the 1940s, 1 in the 1990s, 1 in the 2000s, 1 in the 2010s. Each code after the first was split off from or overlaid on one already in service.
- 1947 203 goes into service.
- 1995 860 goes into service, split from or overlaid on 203.
- 2009 475 goes into service, split from or overlaid on 203.
- 2014 959 goes into service, split from or overlaid on 860.
Time zones
Connecticut is in Eastern time.
Frequently asked about Connecticut area codes
How many area codes does Connecticut have?
4 in service. They are 203, 475, 860 and 959.
What is the oldest area code in Connecticut?
203, in service since 1947. Every later code in the state was split off from or overlaid on an existing one.
What is the newest area code in Connecticut?
959, from 2014, overlaying 860.
Is Connecticut running out of numbers?
203 and 860 are at or past 95% of capacity, but NANPA has not opened relief planning for them, so no new code is announced.
What time zone is Connecticut in?
Eastern time.
Which Connecticut area code gets the most spam complaints?
860 – 755 FTC complaints in the 33 days to 30 October 2026, 120th of 422 codes nationally. Those are complaints about the caller ID shown, and spam callers routinely fake a local-looking number, so this says the code is imitated often, not that the calls come from there.
Which carrier holds the most Connecticut numbers?
AT&T, with 44.9% of the 2,023 blocks assigned across Connecticut, ahead of Verizon at 14.9%. This is allocation of blocks by the numbering administrator, not a count of subscribers – people keep their numbers when they switch carriers.
Do you have to dial 10 digits in Connecticut?
Yes. Every code in the state is in an overlay or ten-digit dialing area, so a local call needs the area code too. Dialing seven digits reaches a recording, not a wrong number.
Sources and verification
- NANPA – NPA Database (npa_report.csv), file date 11/01/2026, retrieved Nov 1, 2026
- NANPA – CO Code Assignment Records, All States (utilized), file updated 11/01/2026, retrieved Nov 1, 2026
- FTC – Do Not Call Reported Calls Data, 28 Sep – 30 Oct 2026, retrieved Nov 1, 2026
Figures on this page are counted from those files, not copied from other sites. Spotted an error? Request a correction. How we collect and check: methodology.