North Carolina, United States
Eastern Time
5:56 PM
Area Code
336
State / Province
North Carolina
Country
United States
Time Zone
Eastern Time
Area code 336 covers 88 cities and communities across North Carolina, based on telephone company rate center data.
Use the E.164 format for clickable phone links (RFC 3966):
<a href="tel:+13365550100">+13365550100</a><a href="tel:+13365550199">+13365550199</a>Look up which exchange in North Carolina a specific 336 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 5,986 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 5,986
| NPA-NXX | Block | Rate centre | Type | Carrier (OCN) | Switch | LATA | LIR | Dates |
|---|---|---|---|---|---|---|---|---|
| 336-200 | 0 | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-200 | 1 | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-200 | 2 | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-200 | 3 | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-200 | 4 | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-200 | 5 | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-200 | 6 | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-200 | 7 | Roaring Gap | Landline or VoIP | LEVEL 3 COMMUNICATIONS, LLC - NC (3235) | GNBONCCKX9X | 424 | — | — |
| 336-200 | 8 | Roaring Gap | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - NC (998E) | GNBONCEU27Z | 424 | — | — |
| 336-200 | 9 | Roaring Gap | Landline or VoIP | CHARTER IP ENABLED SERVICES, LLC (792K) | NWBONC021MD | 424 | — | — |
| 336-200 | A | Roaring Gap | Wireless | UNITED STATES CELLULAR - NC (6282) | ELKNNCAF1MD | 424 | — | — |
| 336-201 | 0 | Winston-Salem | Landline or VoIP | LEVEL 3 TELECOM OF NORTH CAROLINA, LP - NC (7973) | GREENSBORO | 424 | — | — |
| 336-201 | 1 | Winston-Salem | Landline or VoIP | METROPCS, INC. (5562) | GNBONCEU65Z | 424 | — | — |
| 336-201 | 2 | Winston-Salem | Landline or VoIP | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NC (7835) | GNBONCCKX5X | 424 | — | — |
| 336-201 | 3 | Winston-Salem | Landline or VoIP | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NC (7835) | GNBONCCKX5X | 424 | — | — |
| 336-201 | 4 | Winston-Salem | Landline or VoIP | LEVEL 3 TELECOM OF NORTH CAROLINA, LP - NC (7973) | GREENSBORO | 424 | — | — |
| 336-201 | 5 | Winston-Salem | Landline or VoIP | LEVEL 3 TELECOM OF NORTH CAROLINA, LP - NC (7973) | GREENSBORO | 424 | — | — |
| 336-201 | 6 | Winston-Salem | Landline or VoIP | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NC (7835) | GNBONCCKX5X | 424 | — | — |
| 336-201 | 7 | Winston-Salem | Landline or VoIP | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NC (7835) | GNBONCCKX5X | 424 | — | — |
| 336-201 | 8 | Winston-Salem | Landline or VoIP | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NC (7835) | GNBONCCKX5X | 424 | — | — |
| 336-201 | 9 | Winston-Salem | Landline or VoIP | LEVEL 3 TELECOM OF NORTH CAROLINA, LP - NC (7973) | GREENSBORO | 424 | — | — |
| 336-201 | A | Winston-Salem | Landline or VoIP | LEVEL 3 TELECOM OF NORTH CAROLINA, LP - NC (7973) | GREENSBORO | 424 | — | — |
| 336-202 | A | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-203 | 0 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 1 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 2 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 3 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 4 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 5 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 6 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 7 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 8 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | 9 | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-203 | A | Greensboro | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-205 | A | Reidsville | Landline or VoIP | SPOK, INC. (6630) | GNBONCEU51Z | 424 | — | — |
| 336-206 | 0 | Baldwin | Landline or VoIP | CHARTER IP ENABLED SERVICES, LLC (792K) | NWBONC021MD | 424 | — | — |
| 336-206 | A | Baldwin | Landline or VoIP | CHARTER IP ENABLED SERVICES, LLC (792K) | NWBONC021MD | 424 | — | — |
| 336-207 | 0 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 1 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 2 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 3 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 4 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 5 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 6 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 7 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 8 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | 9 | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-207 | A | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-208 | A | Winston-Salem | Landline or VoIP | SPOK, INC. (6630) | GNBONCEU51Z | 424 | — | — |
| 336-209 | A | Greensboro | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-210 | A | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-212 | 0 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 1 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 2 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 3 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 4 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 5 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 6 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 7 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 8 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | 9 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-212 | A | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-213 | A | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-214 | A | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-215 | 0 | Greensboro | Landline or VoIP | METROPCS, INC. (5562) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 1 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 2 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 3 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 4 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 5 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 6 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 7 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 8 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | 9 | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-215 | A | Greensboro | Wireless | SUNCOM DBA T-MOBILE USA (8645) | GNBONCEU65Z | 424 | — | — |
| 336-216 | A | Greensboro | Landline or VoIP | SPOK, INC. (6630) | GNBONCEU51Z | 424 | — | — |
| 336-217 | A | Greensboro | Landline or VoIP | LEVEL 3 TELECOM OF NORTH CAROLINA, LP - NC (7973) | GREENSBORO | 424 | — | — |
| 336-218 | 0 | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-218 | 1 | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-218 | 2 | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-218 | 3 | Greensboro | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - NC (998E) | GNBONCEU27Z | 424 | — | — |
| 336-218 | 4 | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-218 | 5 | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-218 | 6 | Greensboro | Landline or VoIP | LEVEL 3 COMMUNICATIONS, LLC - NC (3235) | GNBONCCKX9X | 424 | — | — |
| 336-218 | 7 | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-218 | 8 | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-218 | 9 | Greensboro | Landline or VoIP | BANDWIDTH.COM CLEC, LLC - NC (998E) | GNBONCEU27Z | 424 | — | — |
| 336-218 | A | Greensboro | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | GREENSBORO ASHLAND DR | 424 | — | — |
| 336-219 | A | West Jefferson | Landline | BRIGHTSPEED OF NORTH CAROLINA, LLC (0471) | WEST JEFFERSON | 424 | — | — |
| 336-220 | A | Churchland | Landline | SURRY TEL. MEMBERSHIP CORP. (0497) | REEDS | 424 | — | — |
| 336-221 | 0 | Burlington | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | BURLINGTON DAVIS | 424 | — | — |
| 336-221 | 1 | Burlington | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | BURLINGTON DAVIS | 424 | — | — |
| 336-221 | 2 | Burlington | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | BURLINGTON DAVIS | 424 | — | — |
| 336-221 | 3 | Burlington | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-221 | 4 | Burlington | Wireless | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC (6324) | KRVLNCARBMD | 424 | — | — |
| 336-221 | 5 | Burlington | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | BURLINGTON DAVIS | 424 | — | — |
| 336-221 | 6 | Burlington | Landline or VoIP | METROPCS, INC. (5562) | GNBONCEU65Z | 424 | — | — |
| 336-221 | 7 | Burlington | Landline or VoIP | ONVOY, LLC - NC (638E) | GNBONCEU24Z | 424 | — | — |
| 336-221 | 8 | Burlington | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | BURLINGTON DAVIS | 424 | — | — |
| 336-221 | 9 | Burlington | Landline | BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL (9417) | BURLINGTON DAVIS | 424 | — | — |
Block-level assignments from the North American Numbering Plan administrator, via localcallingguide.com.
Assigned Prefixes
783
Assignment Blocks
5,986
Rate Centers
88
Carriers of Record
58
| Type | Blocks | Share |
|---|---|---|
| Landline | 1,490 | 25% |
| Landline or VoIP | 2,321 | 39% |
| Wireless | 2,175 | 36% |
| Carrier | Blocks |
|---|---|
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - NC | 851 |
| BELLSOUTH TELECOMM INC DBA SOUTHERN BELL TEL & TEL | 796 |
| SUNCOM DBA T-MOBILE USA | 739 |
| ONVOY, LLC - NC | 465 |
| NEW CINGULAR WIRELESS PCS, LLC - GA | 402 |
| BANDWIDTH.COM CLEC, LLC - NC | 314 |
| TWC IP ENABLED SERVICES, LLC | 257 |
| BRIGHTSPEED OF NORTH CAROLINA, LLC | 247 |
| PAETEC ITEL, LLC | 246 |
| LEVEL 3 COMMUNICATIONS, LLC - NC | 240 |
| 48 other carriers | 1,429 |
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 |
|---|---|---|
| Greensboro | 188 | 1,368 |
| Winston-Salem | 145 | 1,093 |
| High Point | 53 | 383 |
| Burlington | 51 | 421 |
| Asheboro | 29 | 229 |
| Lexington | 29 | 189 |
| Reidsville | 20 | 170 |
| North Wilkesboro | 14 | 106 |
| Roxboro | 13 | 103 |
| Elkin | 11 | 80 |
| Kernersville | 11 | 89 |
| Mount Airy | 11 | 91 |
| Thomasville | 8 | 58 |
| Eden | 6 | 56 |
| Julian | 6 | 56 |
| Madison | 6 | 36 |
| Summerfield | 6 | 56 |
| Baldwin | 5 | 16 |
| Brooks | 5 | 55 |
| Gibsonville | 5 | 45 |
| Oldtown | 5 | 35 |
| West Jefferson | 5 | 24 |
| Advance | 4 | 33 |
| Dobson | 4 | 24 |
| Level Cross | 4 | 38 |
| Lomax | 4 | 34 |
| Mocksville | 4 | 34 |
| Monticello | 4 | 42 |
| Randleman | 4 | 24 |
| Ruffin | 4 | 44 |
| Yadkinville | 4 | 44 |
| Yanceyville | 4 | 44 |
| Anderson | 3 | 33 |
| Kimesville | 3 | 33 |
| King | 3 | 23 |
| Lewisville | 3 | 23 |
| Milton | 3 | 25 |
| Quaker Gap | 3 | 22 |
| Ramseur | 3 | 33 |
| Saxapahaw | 3 | 33 |
| Shoals | 3 | 26 |
| Sparta | 3 | 11 |
| State Road | 3 | 19 |
| Timberlake | 3 | 32 |
| Walkertown | 3 | 23 |
| Walnut Cove | 3 | 25 |
| Zephyr | 3 | 25 |
| Beulah | 2 | 13 |
| Boomer | 2 | 7 |
| Boonville | 2 | 12 |
| Champion | 2 | 6 |
| Churchland | 2 | 2 |
| Clingman | 2 | 15 |
| Courtney | 2 | 12 |
| Creston | 2 | 15 |
| Danbury | 2 | 22 |
| Denton | 2 | 22 |
| Hays | 2 | 22 |
| Liberty (Randolph) | 2 | 6 |
| Mulberry | 2 | 12 |
| Pilot Mountain | 2 | 12 |
| Prospect Hill | 2 | 21 |
| Red Brush | 2 | 15 |
| Reeds | 2 | 2 |
| Roaring Gap | 2 | 22 |
| Rural Hall | 2 | 22 |
| Sandy Ridge | 2 | 21 |
| Seagrove | 2 | 12 |
| Southmont | 2 | 21 |
| Stanleyville | 2 | 22 |
| Stoneville | 2 | 22 |
| Welcome | 2 | 12 |
| Badin Lake | 1 | 9 |
| Bennett | 1 | 1 |
| Coleridge | 1 | 1 |
| Cooleemee | 1 | 8 |
| East Bend | 1 | 11 |
| Farmer | 1 | 9 |
| Forbush | 1 | 9 |
| Gatewood | 1 | 11 |
| Glade Creek | 1 | 11 |
| Ijames | 1 | 8 |
| Jackson Creek | 1 | 9 |
| Lansing | 1 | 1 |
| Nathans Creek | 1 | 1 |
| Pisgah | 1 | 9 |
| Scottville | 1 | 1 |
| Westfield | 1 | 11 |
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.
Area code 336 is a North American Numbering Plan (NANP) telephone area code assigned to North Carolina, United States. It is one of 10 area codes serving North Carolina. 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. 336 is an active North American Numbering Plan (NANP) area code, currently assigned to North Carolina, United States. It is safe to answer or dial calls using this area code.
Area code 336 covers 88 cities and communities in North Carolina, including Advance, Anderson, Asheboro, Badin Lake, Baldwin, and 83 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 336 area code observe Eastern Time (IANA timezone: America/New_York). Eastern Time is UTC−5 in winter (EST) and UTC−4 in summer (EDT). When placing a call to a 336 number from a different time zone, check the current local time above to avoid calling outside of business hours.
From within North Carolina, dial the 7-digit local number directly if calling within the same rate center, or dial 1 + 336 + 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 1 336 XXX XXXX. The country code for both the United States and Canada in NANP is +1.
Format 336 numbers using E.164 notation as required by RFC 3966: prefix with +1 and omit dashes and parentheses (e.g., +13365550100). This format ensures tel: links work correctly on all mobile browsers and VoIP apps. See the tel: URI formatting guide for complete examples.