San Quintin comprises 21 barangays with an estimated population of 35,898. 19 of its barangays (90%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Alac | 2,541 | 0 | Dead zone: no towers from any source |
| Baligayan | 860 | 0 | Dead zone: no towers from any source |
| Bantog | 3,359 | 0 | Dead zone: no towers from any source |
| Bolintaguen | 326 | 0 | Dead zone: no towers from any source |
| Cabalaoangan | 4,483 | 0 | Dead zone: no towers from any source |
| Cabangaran | 2,177 | 0 | Dead zone: no towers from any source |
| Calomboyan | 656 | 0 | Dead zone: no towers from any source |
| Carayacan | 2,463 | 0 | Dead zone: no towers from any source |
| Casantamarian | 1,380 | 0 | Dead zone: no towers from any source |
| Gonzalo | 2,108 | 0 | Dead zone: no towers from any source |
| Labuan | 573 | 0 | Dead zone: no towers from any source |
| Lagasit | 6,801 | 1 | Crowdsourced signal only (no registered tower) |
| Lumayao | 768 | 0 | Dead zone: no towers from any source |
| Mabini | 145 | 0 | Dead zone: no towers from any source |
| Mantacdang | 257 | 0 | Dead zone: no towers from any source |
| Nangapugan | 2,022 | 0 | Dead zone: no towers from any source |
| Poblacion Zone I | 550 | 1 | Crowdsourced signal only (no registered tower) |
| Poblacion Zone II | 454 | 0 | Dead zone: no towers from any source |
| Poblacion Zone III | 544 | 0 | Dead zone: no towers from any source |
| San Pedro | 596 | 0 | Dead zone: no towers from any source |
| Ungib | 2,835 | 0 | Dead zone: no towers from any source |