Castillejos comprises 14 barangays with an estimated population of 77,855. 4 of its barangays (29%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Balaybay | 17,643 | 1 | Crowdsourced signal only (no registered tower) |
| Buenavista | 2,655 | 0 | Dead zone: no towers from any source |
| Del Pilar | 9,533 | 17 | Crowdsourced signal only (no registered tower) |
| Looc | 2,408 | 0 | Dead zone: no towers from any source |
| Magsaysay | 4,287 | 5 | Crowdsourced signal only (no registered tower) |
| Nagbayan | 9,243 | 0 | Dead zone: no towers from any source |
| Nagbunga | 5,419 | 10 | Crowdsourced signal only (no registered tower) |
| San Agustin | 7,370 | 1 | Crowdsourced signal only (no registered tower) |
| San Jose (Pob.) | 1,679 | 5 | Crowdsourced signal only (no registered tower) |
| San Juan (Pob.) | 802 | 1 | Crowdsourced signal only (no registered tower) |
| San Nicolas | 8,533 | 2 | Crowdsourced signal only (no registered tower) |
| San Pablo (Pob.) | 6,628 | 5 | Crowdsourced signal only (no registered tower) |
| San Roque | 903 | 9 | Crowdsourced signal only (no registered tower) |
| Santa Maria | 752 | 0 | Dead zone: no towers from any source |