331
Area code 331
Illinois, United States
National (331) 555-0123, E.164 +13315550123
How the 239 central office codes (exchanges) of area code 331 were allocated, from the North American Numbering Plan's records: to which carrier, as which line type. A 331 number is mobile, fixed line or VoIP according to its exchange, the three digits after the area code; the allocation is the original one (below).
At a glance
- Country code
- +1
- State
- IL
- Exchanges on record
- 239
- Carriers on record
- 20
- Mobile 108 (45%)
- Fixed line 22 (9%)
- VoIP 94 (39%)
- No line type on record 15 (6%)
- 239 exchanges on record
Most exchanges: T-Mobile 43, Sinch (Inteliquent) 39, Verizon 37.
Check a number
Valid fixed line or mobile number in the United States.
| Country | United States numbering plan |
|---|---|
| Line type | Fixed line or mobile |
| Carrier the block was allocated to | No carrier on record for this prefix |
| E.164 | +13315550123 |
| International | +1 331-555-0123 |
| National | (331) 555-0123 |
| RFC 3966 | tel:+1-331-555-0123 |
Source: North American Numbering Plan Administrator (NANPA); Canadian Numbering Administrator (CNAC); National numbering plan: United States (ITU)
The example is 331-555-0123: 555-0100 to 555-0199 are set aside for fictional use in every area code.
The exchange map
One cell per exchange: blocks 331 2xx to 331 9xx; in each block the row is the tens digit, the column the units digit.
- Mobile 108
- Fixed line 22
- VoIP 94
- No line type on record 15
- Not on record 561
Formats and patterns
| E.164 | +13315550123 |
|---|---|
| International | +1 331-555-0123 |
| National | (331) 555-0123 |
| RFC 3966 (tel: URI) | tel:+1-331-555-0123 |
Any 331 number, in E.164
^\+1331[2-9]\d{6}$+1, the area code, a central office code that does not start with 0 or 1, then four digits.
Mobile exchanges (108 on record)
^\+1331(?:2(?:0[0-356]|1[3-68]|2[0235-79]|3[0-24-6]|4[2356]|5[013467]|6[12689]|7[4-8]|8[03-69]|9[0-46])|3(?:0[0-2457]|1[2-5]|2[1578]|3[02357-9]|4[269]|85)|4(?:[26]5|4[24]|5[247]|72|81)|5(?:51|75|88)|6(?:25|31|4[35])|7(?:0[137]|[157]7|25)|8(?:14|26)|9(?:80|98))\d{4}$Fixed line exchanges (22 on record)
^\+1331(?:2(?:0[7-9]|[15]2|2[18]|3[78]|6[04]|79|81|95)|4(?:01|[26]2|56)|684|702|8(?:01|25))\d{4}$VoIP exchanges (94 on record)
^\+1331(?:2(?:[02]4|1[079]|3[39]|4[0147-9]|5[589]|6[357]|7[0-3]|8[278]|9[7-9])|3(?:0[3689]|1[06-9]|2[02-469]|3[146]|4[013-578]|56|73|88|99)|4(?:00|[26]6|31)|5(?:00|29)|6(?:00|27|42|66|88)|7(?:04|[14]6|32|[58]8|7[15])|8(?:0[0368]|37|50|6[67]|71|88|99)|9(?:0[013]|46|[79]9))\d{4}$The exchange patterns follow the original allocations; a number ported since keeps its digits but not necessarily its carrier or its line type.
Carriers and their exchanges
Every carrier holding exchanges in 331, with the exchanges allocated to it (the three digits after the area code).
| Carrier | Exchanges | Mobile | Fixed line | VoIP | Exchanges held |
|---|---|---|---|---|---|
| T-Mobile | 43 | 43 | 0 | 0 | 200, 202–203, 205–206, 218, 220, 225–226, 230, 236, 242–243, 245–246, 250, 253–254, 261–262, 268–269, 274–275, 283–284, 289, 300–301, 304, 307, 321, 425, 472, 575, 643, 645, 703, 707, 757, 814, 826, 980 |
| Sinch (Inteliquent) | 39 | 0 | 0 | 39 | 204, 217, 224, 239, 241, 244, 249, 255, 258, 263, 265, 270–273, 282, 297–298, 306, 319–320, 322–324, 326, 329, 331, 334, 340–341, 343–344, 347, 666, 716, 771, 800, 850, 871 |
| Verizon | 37 | 33 | 4 | 0 | 201, 212–215, 227, 229, 234, 237, 251, 256, 276, 280, 285–286, 290–291, 294, 302, 305, 312, 314, 327, 339, 342, 346, 442, 444, 452, 457, 462, 481, 625, 701–702, 777, 998 |
| AT&T | 33 | 26 | 6 | 1 | 216, 221–223, 231–232, 235, 238, 252, 257, 260, 266, 277–278, 281, 293, 315, 328, 330, 332–333, 335, 337, 349, 385, 454, 465, 551, 588, 717, 725, 801, 903 |
| Fractel | 18 | 0 | 0 | 18 | 299, 336, 345, 348, 356, 388, 399, 400, 500, 529, 600, 732, 758, 788, 867, 899, 900, 946 |
| Bandwidth.com | 11 | 0 | 0 | 11 | 287, 303, 308, 310, 318, 431, 642, 704, 808, 901, 999 |
| Ton80 Communications | 9 | 0 | 0 | 9 | 288, 373, 426, 466, 627, 688, 746, 837, 866 |
| Lumen | 6 | 0 | 6 | 0 | 207–209, 264, 401, 422 |
| Emergency Networks | 5 | 5 | 0 | 0 | 292, 313, 325, 338, 631 |
| Peerless Network | 5 | 0 | 0 | 5 | 210, 240, 259, 803, 888 |
| Comcast | 4 | 0 | 0 | 4 | 248, 775, 806, 979 |
| COMMIO LLC | 3 | 0 | 0 | 3 | 309, 316–317 |
| Paetec Itel | 2 | 0 | 2 | 0 | 228, 279 |
| TELNYX | 2 | 0 | 0 | 2 | 219, 233 |
| Vonage | 2 | 0 | 0 | 2 | 247, 267 |
| Astound Broadband | 1 | 0 | 1 | 0 | 684 |
| DNA Communications | 1 | 0 | 1 | 0 | 825 |
| Dish Wireless | 1 | 1 | 0 | 0 | 296 |
| First Communications | 1 | 0 | 1 | 0 | 456 |
| Nuso | 1 | 0 | 1 | 0 | 295 |
Questions developers ask
- Where is area code 331?
- Area code 331 is in Illinois, in the United States: all 239 of its exchanges on record are there. From abroad it is dialled +1 331, then the seven-digit number.
- Is a 331 number mobile or landline?
- Either: in the North American Numbering Plan the line type belongs to the exchange (the three digits after the area code), not to the area code. Of the 239 exchanges on record in 331, 108 (45%) were allocated as mobile, 22 (9%) as fixed line, 94 (39%) as VoIP and 15 (6%) have no line type on record. A number can have been ported since, to another carrier and even to another line type.
- Which carriers have numbers in area code 331?
- 20 carriers hold exchanges in 331 on record; the most: T-Mobile (43), Sinch (Inteliquent) (39) and Verizon (37). These are the original allocations: with number portability, a number may be served by another carrier today, which only a live carrier lookup (an HLR or MNP query) can tell.
- How do I validate a 331 phone number?
- In E.164 a 331 number matches ^\+1331[2-9]\d{6}$: +1, the area code, a central office code that does not start with 0 or 1, then four digits. Written nationally it reads (331) 555-0123. The exchange patterns on this page narrow it to the exchanges allocated as mobile, fixed line or VoIP.