San Ildefonso comprises 15 barangays with an estimated population of 7,653. 11 of its barangays (73%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Arnap | 354 | 0 | Dead zone: no towers from any source |
| Bahet | 1,190 | 2 | Crowdsourced signal only (no registered tower) |
| Belen | 37 | 0 | Dead zone: no towers from any source |
| Bungro | 1,029 | 0 | Dead zone: no towers from any source |
| Busiing Norte | 594 | 0 | Dead zone: no towers from any source |
| Busiing Sur | 567 | 0 | Dead zone: no towers from any source |
| Dongalo | 473 | 0 | Dead zone: no towers from any source |
| Gongogong | 692 | 3 | Crowdsourced signal only (no registered tower) |
| Iboy | 381 | 0 | Dead zone: no towers from any source |
| Kinamantirisan | 128 | 2 | Crowdsourced signal only (no registered tower) |
| Otol-Patac | 459 | 0 | Dead zone: no towers from any source |
| Poblacion East | 906 | 9 | Crowdsourced signal only (no registered tower) |
| Poblacion West | 228 | 0 | Dead zone: no towers from any source |
| Sagneb | 141 | 0 | Dead zone: no towers from any source |
| Sagsagat | 474 | 0 | Dead zone: no towers from any source |