Siayan comprises 22 barangays with an estimated population of 36,211. 22 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 |
|---|---|---|---|
| Balok | 929 | 0 | Dead zone: no towers from any source |
| Balunokan | 382 | 0 | Dead zone: no towers from any source |
| Datagan | 2,745 | 0 | Dead zone: no towers from any source |
| Denoyan | 270 | 0 | Dead zone: no towers from any source |
| Diongan | 1,229 | 0 | Dead zone: no towers from any source |
| Domogok | 1,156 | 0 | Dead zone: no towers from any source |
| Dumpilas | 143 | 0 | Dead zone: no towers from any source |
| Gonayen | 1,021 | 0 | Dead zone: no towers from any source |
| Guibo | 4,189 | 0 | Dead zone: no towers from any source |
| Gunyan | 3,204 | 0 | Dead zone: no towers from any source |
| Litolet | 435 | 0 | Dead zone: no towers from any source |
| Macasing | 4,068 | 0 | Dead zone: no towers from any source |
| Mangilay | 755 | 0 | Dead zone: no towers from any source |
| Moyo | 1,898 | 0 | Dead zone: no towers from any source |
| Muñoz | 2,568 | 0 | Dead zone: no towers from any source |
| Pange | 1,212 | 0 | Dead zone: no towers from any source |
| Paranglumba (Pob.) | 3,142 | 0 | Dead zone: no towers from any source |
| Polayo | 250 | 0 | Dead zone: no towers from any source |
| Sayaw | 1,574 | 0 | Dead zone: no towers from any source |
| Seriac | 1,827 | 0 | Dead zone: no towers from any source |
| Siayan Proper (Pob.) | 2,815 | 0 | Dead zone: no towers from any source |
| Suguilon | 399 | 0 | Dead zone: no towers from any source |