San Isidro comprises 9 barangays with an estimated population of 5,550. 8 of its barangays (89%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Cabayogan | 198 | 0 | Dead zone: no towers from any source |
| Dalimag | 509 | 0 | Dead zone: no towers from any source |
| Langbaban | 193 | 0 | Dead zone: no towers from any source |
| Manayday | 713 | 0 | Dead zone: no towers from any source |
| Pantoc | 478 | 0 | Dead zone: no towers from any source |
| Poblacion | 930 | 3 | Crowdsourced signal only (no registered tower) |
| Sabtan-olo | 787 | 0 | Dead zone: no towers from any source |
| San Marcial | 1,306 | 0 | Dead zone: no towers from any source |
| Tangbao | 436 | 0 | Dead zone: no towers from any source |