Santiago comprises 24 barangays with an estimated population of 18,120. 10 of its barangays (42%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Al-aludig | 637 | 0 | Dead zone: no towers from any source |
| Ambucao | 1,042 | 0 | Dead zone: no towers from any source |
| Baybayabas | 505 | 0 | Dead zone: no towers from any source |
| Bigbiga | 630 | 9 | Crowdsourced signal only (no registered tower) |
| Bulbulala | 615 | 2 | Crowdsourced signal only (no registered tower) |
| Busel-busel | 281 | 1 | Crowdsourced signal only (no registered tower) |
| Butol | 595 | 1 | Crowdsourced signal only (no registered tower) |
| Caburao | 1,277 | 9 | Crowdsourced signal only (no registered tower) |
| Dan-ar | 2,348 | 6 | Crowdsourced signal only (no registered tower) |
| Gabao | 671 | 0 | Dead zone: no towers from any source |
| Guinabang | 196 | 0 | Dead zone: no towers from any source |
| Imus | 400 | 2 | Crowdsourced signal only (no registered tower) |
| Lang-ayan | 484 | 1 | Crowdsourced signal only (no registered tower) |
| Mambug | 1,338 | 0 | Dead zone: no towers from any source |
| Nalasin | 338 | 0 | Dead zone: no towers from any source |
| Olo-olo Norte | 1,295 | 6 | Crowdsourced signal only (no registered tower) |
| Olo-olo Sur | 490 | 2 | Crowdsourced signal only (no registered tower) |
| Poblacion Norte | 879 | 3 | Crowdsourced signal only (no registered tower) |
| Poblacion Sur | 341 | 1 | Crowdsourced signal only (no registered tower) |
| Sabangan | 1,010 | 0 | Dead zone: no towers from any source |
| Salincub | 862 | 0 | Dead zone: no towers from any source |
| San Jose (Baraoas) | 370 | 2 | Crowdsourced signal only (no registered tower) |
| San Roque | 820 | 0 | Dead zone: no towers from any source |
| Ubbog | 696 | 1 | Crowdsourced signal only (no registered tower) |