San Mariano comprises 36 barangays with an estimated population of 85,420. 31 of its barangays (86%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Alibadabad | 2,565 | 7 | Crowdsourced signal only (no registered tower) |
| Balagan | 1,848 | 0 | Dead zone: no towers from any source |
| Binatug | 2,628 | 0 | Dead zone: no towers from any source |
| Bitabian | 1,067 | 0 | Dead zone: no towers from any source |
| Buyasan | 546 | 0 | Dead zone: no towers from any source |
| Cadsalan | 2,112 | 0 | Dead zone: no towers from any source |
| Casala | 1,513 | 0 | Dead zone: no towers from any source |
| Cataguing | 4,991 | 3 | Crowdsourced signal only (no registered tower) |
| Daragutan East | 1,828 | 0 | Dead zone: no towers from any source |
| Daragutan West | 3,788 | 0 | Dead zone: no towers from any source |
| Del Pilar | 847 | 0 | Dead zone: no towers from any source |
| Dibuluan | 4,049 | 0 | Dead zone: no towers from any source |
| Dicamay | 3,189 | 0 | Dead zone: no towers from any source |
| Dipusu | 954 | 0 | Dead zone: no towers from any source |
| Disulap | 4,699 | 0 | Dead zone: no towers from any source |
| Disusuan | 1,919 | 0 | Dead zone: no towers from any source |
| Gangalan | 1,051 | 0 | Dead zone: no towers from any source |
| Ibujan | 863 | 0 | Dead zone: no towers from any source |
| Libertad | 1,141 | 0 | Dead zone: no towers from any source |
| Macayucayu | 1,558 | 0 | Dead zone: no towers from any source |
| Mallabo | 450 | 0 | Dead zone: no towers from any source |
| Marannao | 2,181 | 0 | Dead zone: no towers from any source |
| Minanga | 7,670 | 0 | Dead zone: no towers from any source |
| Old San Mariano | 2,069 | 0 | Dead zone: no towers from any source |
| Palutan | 1,730 | 0 | Dead zone: no towers from any source |
| Panninan | 2,077 | 0 | Dead zone: no towers from any source |
| San Jose | 3,758 | 0 | Dead zone: no towers from any source |
| San Pablo | 869 | 0 | Dead zone: no towers from any source |
| San Pedro | 1,181 | 0 | Dead zone: no towers from any source |
| Santa Filomina | 3,508 | 4 | Crowdsourced signal only (no registered tower) |
| Tappa | 2,681 | 0 | Dead zone: no towers from any source |
| Ueg | 4,276 | 0 | Dead zone: no towers from any source |
| Zamora | 440 | 0 | Dead zone: no towers from any source |
| Zone I (Pob.) | 2,462 | 2 | Crowdsourced signal only (no registered tower) |
| Zone II (Pob.) | 1,678 | 0 | Dead zone: no towers from any source |
| Zone III (Pob.) | 5,234 | 11 | Crowdsourced signal only (no registered tower) |