| City/Town/Village | State/UT/Region | Company | Technology | Customer Care Nos. |
| Oddanchatram | Tamil Nadu / Pondicherry | Aircel Ltd. | GSM | 9842212345 |
| Ode | Gujarat | IDEA Cellular | GSM | 9824012345 |
| Ojhar | Maharashtra / Goa | BPL Cellular | GSM | 9823099800 |
| Olavakkode | Kerala | AirTel | GSM | 9895012345 |
| IDEA Cellular | GSM | 9847012345 | ||
| BPL Cellular | GSM | 9846098460 | ||
| OldGoa | Maharashtra / Goa | IDEA Cellular | GSM | 9822012345 |
| BPL Cellular | GSM | 9823099800 | ||
| Airtel | GSM | 9890012345 | ||
| Ollur | Kerala | AirTel | GSM | 9895012345 |
| BPL Cellular | GSM | 9846098460 | ||
| IDEA Cellular | GSM | 9847012345 | ||
| Olpad | Tata Indicom | CDMA | 9210008282 | |
| Omalur | hw | Tata Indicom | CDMA | 9210008282 |
| Ongole | Andhra Pradesh | HUTCH | GSM | 9885000111 |
| IDEA Cellular | GSM | 9848012345 | ||
| Airtel | GSM | 9849012345 | ||
| Tata Indicom | CDMA | 9210008282 | ||
| Ooty | Tamil Nadu / Pondicherry | Aircel Ltd. | GSM | 9842212345 |
| BPL Cellular | GSM | 9843098430 | ||
| Orlim | Maharashtra / Goa | AirTel | GSM | 9890012345 |
| Osmanabad | Maharashtra / Goa | IDEA Cellular | GSM | 9822012345 |
| Airtel | GSM | 9890012345 | ||
| Tata Indicom | CDMA | 9210008282 | ||
| Otanchathiram | Tamil Nadu / Pondicherry | BPL Cellular | GSM | 9843098430 |
| Othiyur | hw | Tata Indicom | CDMA | 9210008282 |
| Ottanchatram | Tata Indicom | CDMA | 9210008282 | |
| Ottapalam | Kerala | BPL Cellular | GSM | 9846098460 |
| IDEA Cellular | GSM | 9847012345 | ||
| Ozar | Maharashtra / Goa | BPL Cellular | GSM | 9823099800 |
| Airtel | GSM | 9890012345 | ||
| IDEA Cellular | GSM | 9822012345 |