California, United States
Pacific Time
11:55 PM
Area Code
530
State / Province
California
Country
United States
Time Zone
Pacific Time
Area code 530 covers 126 cities and communities across California, based on telephone company rate center data.
Use the E.164 format for clickable phone links (RFC 3966):
<a href="tel:+15305550100">+15305550100</a><a href="tel:+15305550199">+15305550199</a>Look up which exchange in California a specific 530 number is homed to, and whether its block is wireline or wireless. See what a reverse lookup can establish before relying on the answer.
783 active prefixes in this area code, assigned as 6,453 thousands-blocks — pooling splits one prefix across several carriers, so each block is listed separately with the rate centre it is homed to, its carrier of record, and the switch that serves it.
Showing blocks 1–100 of 6,453
| NPA-NXX | Block | Rate centre | Type | Carrier (OCN) | Switch | LATA | LIR | Dates |
|---|---|---|---|---|---|---|---|---|
| 530-200 | 0 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 1 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 2 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 3 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 4 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 5 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 6 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 7 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | 8 | Los Molinos | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-200 | 9 | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-200 | A | Los Molinos | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | CHICO | 724 | — | — |
| 530-201 | 0 | Redding | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | CHICCAEYKMD | 724 | — | — |
| 530-201 | 1 | Redding | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | CHICCAEYKMD | 724 | — | — |
| 530-201 | 2 | Redding | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | CHICCAEYKMD | 724 | — | — |
| 530-201 | 3 | Redding | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-201 | 4 | Redding | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-201 | 5 | Redding | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-201 | 6 | Redding | Wireless | T-MOBILE USA, INC. (6529) | CHICCA01RMD | 724 | — | — |
| 530-201 | 7 | Redding | Wireless | T-MOBILE USA, INC. (6529) | CHICCA01RMD | 724 | — | — |
| 530-201 | 8 | Redding | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | CHICCAEYKMD | 724 | — | — |
| 530-201 | 9 | Redding | Wireless | T-MOBILE USA, INC. (6529) | CHICCA01RMD | 724 | — | — |
| 530-201 | A | Redding | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-202 | 0 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 1 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 2 | Auburn: Main DA | Wireless | ONVOY SPECTRUM, LLC (624H) | SCRMCA0101Z | 726 | — | — |
| 530-202 | 3 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 4 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 5 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 6 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 7 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 8 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | 9 | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-202 | A | Auburn: Main DA | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-203 | 0 | Elk Creek | Landline or VoIP | TELNYX LLC (073H) | CHICCACW1MD | 724 | — | — |
| 530-203 | 1 | Elk Creek | Landline or VoIP | IP HORIZON LLC (515J) | — | 724 | — | — |
| 530-203 | 2 | Elk Creek | Landline or VoIP | IP HORIZON LLC (515J) | — | 724 | — | — |
| 530-203 | 3 | Elk Creek | Landline or VoIP | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS (671J) | CHICCA01XQX | 724 | — | — |
| 530-203 | 4 | Elk Creek | Landline or VoIP | TELNYX LLC (073H) | CHICCACW1MD | 724 | — | — |
| 530-203 | 5 | Elk Creek | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-203 | 6 | Elk Creek | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-203 | 7 | Elk Creek | Landline or VoIP | TELNYX LLC (073H) | CHICCA01XDX | 724 | — | — |
| 530-203 | 8 | Elk Creek | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-203 | 9 | Elk Creek | Landline or VoIP | ONVOY, LLC - CA (649C) | CHICCA01XCX | 724 | — | — |
| 530-203 | A | Elk Creek | Landline or VoIP | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS (671J) | CHICCA01XQX | 724 | — | — |
| 530-204 | 0 | Davis | Landline or VoIP | METROPCS, INC. (5562) | WSCRCAKE1MD | 726 | — | — |
| 530-204 | 1 | Davis | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-204 | 2 | Davis | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-204 | 3 | Davis | Landline or VoIP | METROPCS, INC. (5562) | WSCRCAKE1MD | 726 | — | — |
| 530-204 | 4 | Davis | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-204 | 5 | Davis | Landline or VoIP | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA (7128) | WEST SACRAMENTO | 726 | — | — |
| 530-204 | 6 | Davis | Landline or VoIP | METROPCS, INC. (5562) | WSCRCAKE1MD | 726 | — | — |
| 530-204 | 7 | Davis | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-204 | 8 | Davis | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-204 | 9 | Davis | Landline or VoIP | METROPCS, INC. (5562) | WSCRCAKE1MD | 726 | — | — |
| 530-204 | A | Davis | Landline or VoIP | IP HORIZON LLC (515J) | SCRMCA0110Z | 726 | — | — |
| 530-205 | 0 | Grass Valley: Main DA | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-205 | 1 | Grass Valley: Main DA | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-205 | 2 | Grass Valley: Main DA | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-205 | 3 | Grass Valley: Main DA | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-205 | 4 | Grass Valley: Main DA | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-205 | 5 | Grass Valley: Main DA | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-205 | 6 | Grass Valley: Main DA | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-205 | 7 | Grass Valley: Main DA | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-205 | 8 | Grass Valley: Main DA | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-205 | 9 | Grass Valley: Main DA | Landline or VoIP | COMCAST PHONE OF CALIFORNIA, LLC (394L) | SCRMCA0111Z | 726 | — | — |
| 530-205 | A | Grass Valley: Main DA | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-206 | 0 | Placerville: Kyburz DA | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-206 | 1 | Placerville: Kyburz DA | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-206 | 2 | Placerville: Kyburz DA | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-206 | 3 | Placerville: Kyburz DA | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-206 | 4 | Placerville: Kyburz DA | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-206 | 5 | Placerville: Kyburz DA | Landline or VoIP | ONVOY, LLC - CA (649C) | SCRMCA01XSY | 726 | — | — |
| 530-206 | 6 | Placerville: Kyburz DA | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA (6006) | WSCRCAAHNMD | 726 | — | — |
| 530-206 | 7 | Placerville: Kyburz DA | Landline or VoIP | ONVOY, LLC - CA (649C) | SCRMCA01XSY | 726 | — | — |
| 530-206 | 8 | Placerville: Kyburz DA | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-206 | 9 | Placerville: Kyburz DA | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-206 | A | Placerville: Kyburz DA | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-207 | 0 | Woodland | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-207 | 1 | Woodland | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-207 | 2 | Woodland | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-207 | 3 | Woodland | Landline or VoIP | ONVOY, LLC - CA (649C) | SCRMCA01XSY | 726 | — | — |
| 530-207 | 4 | Woodland | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-207 | 5 | Woodland | Landline or VoIP | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS (671J) | SCRMCA0121Z | 726 | — | — |
| 530-207 | 6 | Woodland | Landline or VoIP | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA (7128) | WEST SACRAMENTO | 726 | — | — |
| 530-207 | 7 | Woodland | Landline or VoIP | METROPCS, INC. (5562) | WSCRCAKE1MD | 726 | — | — |
| 530-207 | 8 | Woodland | Landline or VoIP | ONVOY, LLC - CA (649C) | SCRMCA01XSY | 726 | — | — |
| 530-207 | 9 | Woodland | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-207 | A | Woodland | Landline or VoIP | IP HORIZON LLC (515J) | SCRMCA0110Z | 726 | — | — |
| 530-208 | 0 | South Tahoe | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-208 | 1 | South Tahoe | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-208 | 2 | South Tahoe | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-208 | 3 | South Tahoe | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-208 | 4 | South Tahoe | Landline or VoIP | IP HORIZON LLC (515J) | — | 726 | — | — |
| 530-208 | 5 | South Tahoe | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-208 | 6 | South Tahoe | Wireless | T-MOBILE USA, INC. (6529) | WSCRCAKE1MD | 726 | — | — |
| 530-208 | 7 | South Tahoe | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | SCRMCA01GT1 | 726 | — | — |
| 530-208 | 8 | South Tahoe | Wireless | NEW CINGULAR WIRELESS PCS, LLC (6010) | SCRMCA01GT1 | 726 | — | — |
| 530-208 | 9 | South Tahoe | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-208 | A | South Tahoe | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - CA (981E) | SCRMCA01XXY | 726 | — | — |
| 530-209 | 0 | Redding | Wireless | T-MOBILE USA, INC. (6529) | CHICCA01RMD | 724 | — | — |
Block-level assignments from the North American Numbering Plan administrator, via localcallingguide.com.
Assigned Prefixes
783
Assignment Blocks
6,453
Rate Centers
132
Carriers of Record
62
| Type | Blocks | Share |
|---|---|---|
| Landline | 1,077 | 17% |
| Landline or VoIP | 3,515 | 54% |
| Wireless | 1,861 | 29% |
| Carrier | Blocks |
|---|---|
| ONVOY, LLC - CA | 1,107 |
| PACIFIC BELL | 828 |
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA | 625 |
| NEW CINGULAR WIRELESS PCS, LLC | 602 |
| T-MOBILE USA, INC. | 463 |
| BANDWIDTH.COM CLEC, LLC - CA | 455 |
| LEVEL 3 COMMUNICATIONS, LLC - CA | 300 |
| METROPCS, INC. | 244 |
| IP HORIZON LLC | 218 |
| COMMIO, LLC | 144 |
| 52 other carriers | 1,467 |
Carrier of record for each block. Numbers ported to another carrier keep their original block assignment, so this is not a lookup of who serves a given number today.
| Rate Center | Prefixes | Blocks |
|---|---|---|
| Chico | 64 | 449 |
| Redding | 60 | 455 |
| Marysville | 53 | 468 |
| Auburn: Main DA | 38 | 345 |
| Davis | 33 | 264 |
| Woodland | 26 | 240 |
| Placerville: West DA | 25 | 179 |
| Grass Valley: Main DA | 23 | 144 |
| Oroville | 22 | 207 |
| South Tahoe | 19 | 183 |
| Red Bluff | 14 | 119 |
| Truckee | 13 | 113 |
| Shingle Springs | 12 | 91 |
| Anderson | 11 | 105 |
| Yreka | 10 | 83 |
| Nevada City | 9 | 88 |
| Paradise | 9 | 72 |
| Mount Shasta | 8 | 62 |
| North Tahoe: Tahoe City DA | 8 | 77 |
| Susanville | 8 | 70 |
| Corning | 7 | 54 |
| Alleghany | 6 | 60 |
| Biggs | 6 | 61 |
| Colfax: Colfax DA | 6 | 48 |
| Georgetown | 6 | 62 |
| Live Oak | 6 | 59 |
| Orland | 6 | 45 |
| Placerville: Kyburz DA | 6 | 64 |
| Quincy | 6 | 60 |
| Willows | 6 | 47 |
| Auburn: North DA | 5 | 46 |
| Cottonwood | 5 | 46 |
| Grass Valley: South DA | 5 | 49 |
| Gridley | 5 | 48 |
| North San Juan | 5 | 34 |
| North Tahoe: Brockway DA | 5 | 52 |
| North Yuba | 5 | 36 |
| Placerville: South DA | 5 | 53 |
| Weaverville | 5 | 37 |
| Winters | 5 | 47 |
| Alta | 4 | 43 |
| Bangor | 4 | 27 |
| Blairsden | 4 | 34 |
| Butte City | 4 | 36 |
| Camptonville | 4 | 42 |
| Challenge | 4 | 32 |
| Downieville | 4 | 32 |
| Dunnigan | 4 | 38 |
| Homewood | 4 | 43 |
| Los Molinos | 4 | 44 |
| Loyalton | 4 | 39 |
| Meridian | 4 | 39 |
| Soda Springs | 4 | 35 |
| Weed | 4 | 37 |
| Wheatland | 4 | 41 |
| Williams | 4 | 37 |
| Alturas | 3 | 21 |
| Chester | 3 | 25 |
| Colfax: Weimar DA | 3 | 30 |
| Colusa | 3 | 24 |
| Dunsmuir | 3 | 31 |
| Elk Creek | 3 | 27 |
| Esparto | 3 | 27 |
| Gazelle | 3 | 23 |
| Gerber | 3 | 23 |
| Hayfork | 3 | 23 |
| Hoopa | 3 | 23 |
| Knights Landing | 3 | 29 |
| Lewiston | 3 | 29 |
| Millville | 3 | 24 |
| Nicolaus | 3 | 27 |
| Paskenta | 3 | 27 |
| Portola | 3 | 33 |
| Richvale | 3 | 28 |
| Robbins | 3 | 30 |
| Shasta Lake | 3 | 30 |
| Sierraville | 3 | 27 |
| Stonyford | 3 | 27 |
| Verdi | 3 | 17 |
| Vina | 3 | 26 |
| Willow Creek | 3 | 26 |
| Arbuckle | 2 | 14 |
| Cedarville | 2 | 10 |
| French Gulch | 2 | 20 |
| Grenada | 2 | 21 |
| Guinda | 2 | 15 |
| Hornbrook | 2 | 22 |
| Janesville | 2 | 15 |
| McCloud | 2 | 14 |
| Montague | 2 | 20 |
| Oak Run | 2 | 4 |
| Olinda | 2 | 2 |
| Orleans | 2 | 18 |
| Princeton | 2 | 15 |
| Rancho Tehama | 2 | 3 |
| Shingletown | 2 | 4 |
| Smartsville | 2 | 22 |
| Westwood | 2 | 10 |
| Adin | 1 | 7 |
| Alpine | 1 | 7 |
| Bieber | 1 | 6 |
| Burney | 1 | 10 |
| Coleville | 1 | 6 |
| Dorris | 1 | 1 |
| Eagle Lake | 1 | 6 |
| Etna | 1 | 1 |
| Fall River Mills | 1 | 11 |
| Foresthill | 1 | 1 |
| Fort Jones | 1 | 1 |
| Greenville | 1 | 9 |
| Grimes | 1 | 6 |
| Hamburg | 1 | 1 |
| Happy Camp | 1 | 1 |
| Herlong | 1 | 10 |
| Keddie | 1 | 5 |
| Lake Almanor | 1 | 6 |
| MacDoel | 1 | 1 |
| Maxwell | 1 | 6 |
| Mineral | 1 | 7 |
| Minersville | 1 | 3 |
| Montgomery Creek | 1 | 8 |
| New Pine Creek | 1 | 1 |
| Newell | 1 | 1 |
| Oak Knoll | 1 | 1 |
| Paynes Creek | 1 | 5 |
| Platina | 1 | 3 |
| Ravendale | 1 | 8 |
| Sacramento: Main DA | 1 | 1 |
| Sawyers Bar | 1 | 1 |
| Somes Bar | 1 | 1 |
| Trinity Center | 1 | 3 |
| Tulelake | 1 | 1 |
A rate center is the telephone exchange area a number is homed to. It sets local calling boundaries, and is not the caller's current location.
530 now shares its territory with 837. Because of this overlay, local calls in this region must be dialed with all ten digits.
Area code 530 is a North American Numbering Plan (NANP) telephone area code assigned to California, United States. It is one of 41 area codes serving California. As population and demand for phone numbers grew, the region was divided into multiple numbering plan areas to avoid exhausting the available 7-digit number pool.
Yes. 530 is an active North American Numbering Plan (NANP) area code, currently assigned to California, United States. It is safe to answer or dial calls using this area code.
Area code 530 covers 126 cities and communities in California, including Adin, Alleghany, Alpine, Alta, Alturas, and 121 more localities. This is based on telephone company rate center data — the geographic areas carriers use to determine local calling boundaries and to assign numbers when a business or individual requests a phone number in a specific city.
All numbers in the 530 area code observe Pacific Time (IANA timezone: America/Los_Angeles). Pacific Time is UTC−8 in winter (PST) and UTC−7 in summer (PDT). When placing a call to a 530 number from a different time zone, check the current local time above to avoid calling outside of business hours.
From within California, dial the 7-digit local number directly if calling within the same rate center, or dial 1 + 530 + 7-digit number for long-distance calls within North America. From outside the US or Canada, dial your country's international exit code followed by 1 530 XXX XXXX. The country code for both the United States and Canada in NANP is +1.
Format 530 numbers using E.164 notation as required by RFC 3966: prefix with +1 and omit dashes and parentheses (e.g., +15305550100). This format ensures tel: links work correctly on all mobile browsers and VoIP apps. See the tel: URI formatting guide for complete examples.