| Isabela | |
| Area | Zip |
| Alicia | 3306 |
| Angadanan | 3307 |
| Aurora | 3316 |
| Benito Soliven | 3331 |
| Burgos | 3322 |
| Cabagan | 3328 |
| Cabatuan | 3315 |
| Cauayan | 3305 |
| Cordon | 3312 |
| Delfin Albano | 3326 |
| Dinapigui | 3336 |
| Divilacan | 3335 |
| Echague | 3309 |
| Gamu | 3301 |
| Ilagan | 3300 |
| Jones | 3313 |
| Luna | 3304 |
| Maconacon | 3333 |
| Mallig | 3323 |
| Naguillan | 3302 |
| Palanan | 3334 |
| Quezon | 3324 |
| Quirino | 3321 |
| Ramon | 3319 |
| Reina Mercedes | 3303 |
| Roxas | 3320 |
| San Agustin | 3314 |
| San Guillermo | 3308 |
| San Isidro | 3310 |
| San Manuel (Callang) | 3317 |
| San Mariano | 3332 |
| San Mateo | 3318 |
| San Pablo | 3329 |
| Santa Maria | 3330 |
| Santiago | 3311 |
| Santo Tomas | 3327 |
| Tumauini | 3325 |
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