San Agustin comprises 23 barangays with an estimated population of 21,723. 22 of its barangays (96%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Bautista | 556 | 0 | Dead zone: no towers from any source |
| Calaocan | 271 | 0 | Dead zone: no towers from any source |
| Dabubu Grande | 609 | 0 | Dead zone: no towers from any source |
| Dabubu Pequeño | 377 | 0 | Dead zone: no towers from any source |
| Dappig | 440 | 0 | Dead zone: no towers from any source |
| Laoag | 924 | 0 | Dead zone: no towers from any source |
| Mapalad | 826 | 0 | Dead zone: no towers from any source |
| Masaya Centro (Pob.) | 1,755 | 1 | Crowdsourced signal only (no registered tower) |
| Masaya Norte | 1,873 | 0 | Dead zone: no towers from any source |
| Masaya Sur | 1,511 | 0 | Dead zone: no towers from any source |
| Nemmatan | 985 | 0 | Dead zone: no towers from any source |
| Palacian | 1,754 | 0 | Dead zone: no towers from any source |
| Panang | 562 | 0 | Dead zone: no towers from any source |
| Quimalabasa Norte | 789 | 0 | Dead zone: no towers from any source |
| Quimalabasa Sur | 538 | 0 | Dead zone: no towers from any source |
| Rang-ay | 256 | 0 | Dead zone: no towers from any source |
| Salay | 1,284 | 0 | Dead zone: no towers from any source |
| San Antonio | 503 | 0 | Dead zone: no towers from any source |
| Santo Niño | 3,402 | 0 | Dead zone: no towers from any source |
| Santos | 681 | 0 | Dead zone: no towers from any source |
| Sinaoangan Norte | 609 | 0 | Dead zone: no towers from any source |
| Sinaoangan Sur | 459 | 0 | Dead zone: no towers from any source |
| Virgoneza | 759 | 0 | Dead zone: no towers from any source |