| Hardware and OS | BenQ-Siemens P51 | |
| Operating system | Microsoft Windows Mobile 5.0 PocketPC | |
| Processor | 32-bit Intel XScale PXA272 416 MHz | |
| Internal memory | 64MB RAM, 192MB ROM | |
| External memory | MMC/SDIO | |
| Display | BenQ-Siemens P51 | other phones |
| Size | 2.8 inches, 42 x 57 mm, 24.3 cm2 | |
| Resolution | 240 x 320 pixels, 4:3 ratio | |
| Type | TFT resistive touchscreen, 256K colors | |
| Main Camera | BenQ-Siemens P51 | other phones |
| Camera | 1.3 MP | |
| Video | QCIF | |
| Selfie camera | BenQ-Siemens P51 | other phones |
| Camera | No | |
| Connectivity | BenQ-Siemens P51 | other phones |
| 2G Network | GSM 850 / 900 / 1800 / 1900 | |
| Bluetooth | 1.2, A2DP | |
| EDGE | No | |
| GPRS | Class 10 | |
| GPS | Yes | |
| Technology | GSM | |
| USB | Proprietary | |
| WLAN | Wi-Fi 802.11b/g, VoIP via Wi-Fi | |
| Multimedia | BenQ-Siemens P51 | other phones |
| 3.5 mm Jack | No | |
| Alert types | Vibration; Downloadable polyphonic, MP3 ringtones | |
| Loudspeaker | Yes | |
| Radio | No | |
| Battery | BenQ-Siemens P51 | other phones |
| Capacity | Removable Li-Ion 1370 mAh battery | |
| Stand-by | Up to 150 h | |
| Talk time | Up to 4 h | |
| Design | BenQ-Siemens P51 | other phones |
| Dimensions | 122 x 60 x 20 mm, 130 cc (4.80 x 2.36 x 0.79 in) | |
| Weight | 170 g (6.00 oz) | |
| SIM | Mini-SIM | |
| Keyboard | QWERTY | |
