San Agustin comprises 15 barangays with an estimated population of 17,354. 15 of its barangays (100%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Bachawan | 1,728 | 0 | Dead zone: no towers from any source |
| Binonga-an | 1,795 | 0 | Dead zone: no towers from any source |
| Buli | 595 | 0 | Dead zone: no towers from any source |
| Cabolutan | 1,264 | 0 | Dead zone: no towers from any source |
| Cagbo-aya | 1,753 | 0 | Dead zone: no towers from any source |
| Camantaya | 236 | 0 | Dead zone: no towers from any source |
| Carmen | 1,907 | 0 | Dead zone: no towers from any source |
| Cawayan | 518 | 0 | Dead zone: no towers from any source |
| Doña Juana | 1,225 | 0 | Dead zone: no towers from any source |
| Dubduban | 1,878 | 0 | Dead zone: no towers from any source |
| Hinugusan | 698 | 0 | Dead zone: no towers from any source |
| Lusong | 952 | 0 | Dead zone: no towers from any source |
| Mahabang Baybay (Long Beach) | 1,084 | 0 | Dead zone: no towers from any source |
| Poblacion | 446 | 0 | Dead zone: no towers from any source |
| Sugod | 1,275 | 0 | Dead zone: no towers from any source |