Santiago comprises 9 barangays with an estimated population of 28,402. 3 of its barangays (33%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Curva | 3,828 | 7 | Crowdsourced signal only (no registered tower) |
| Estanislao Morgado | 1,376 | 0 | Dead zone: no towers from any source |
| Jagupit | 4,009 | 2 | Crowdsourced signal only (no registered tower) |
| La Paz | 1,191 | 0 | Dead zone: no towers from any source |
| Pangaylan-IP | 1,334 | 0 | Dead zone: no towers from any source |
| Poblacion I | 4,889 | 1 | Crowdsourced signal only (no registered tower) |
| Poblacion II | 4,618 | 2 | Crowdsourced signal only (no registered tower) |
| San Isidro | 2,556 | 1 | Crowdsourced signal only (no registered tower) |
| Tagbuyacan | 4,601 | 10 | Crowdsourced signal only (no registered tower) |