| Nokia 1661 | Sendo X |
| Manufacture | Nokia | Sendo |
| Model | 1661 | X |
| Form factor | Block | Block |
| Weight | 82 gram | 120.00 |
| Dimensions (HxWxD) | 108 x 45 x 14 | 111.00 x 49.00 x 23.00 |
| Operating System | Other | Other |
| Networks | 2G - 850/900/1800/1900 | 2G - 900/1800/1900 |
| HSCSD |  | NA |
| GPRS |  | |
| EDGE | | |
| UMTS | | |
| HSDPA | | |
| HSPA+ | | |
| WiMAX | | |
| LTE (4G light) | | |
| WLAN / Wi-Fi | | |
| Wi-Fi Hotspot | | |
| Wi-Fi Direct | | |
| SMS | | |
| MMS | | |
| | |
| HDMI out | | |
| USB port | | |
| MHL | | |
| Bluetooth | | |
| Bluetooth version | NA | NA |
| DLNA | | |
| GPS | | |
| Glonass | | |
| ANT+ | | |
| IrDA | | |
| NFC | | |
| 3.5 mm audio connector | | |
| Camera | | |
| Camera resolution | NA | 0.3 megapixel |
| Image Stabilization | | |
| BSI sensor | | |
| Camera Flash/Light | | |
| Flash type | NA | NA |
| Video recording | | |
| Video capture resolution | NA | NA |
| Second Camera | NA | NA |
| Display size | 1.8 inches | 2.20 |
| Touchscreen | | |
| Colour display | | |
| Number of colours | 65000 | 65536 |
| Display width | 128 | 176 |
| Display height | 160 | 220 |
| PPI | 113.83 | 128.06 |
| Second Display | NA | NA |
| CPU | NA | NA |
| GPU | NA | NA |
| Memory | 8 MB | 64MB |
| Micro SIM | | |
| Dual SIM | | |
| MP3 | | |
| Ringtones / Music file format | Polyphonic | Polyphonic 64 voices |
| Java | | |
| Games | Yes | 2 |
| FM Radio | | NA |
| Battery | 860 mAh | Lithium 1050 mAh |
| Standby time (h) | 624 | 170 |
| Talktime (m) | 480 | 420 |
| Wireless Charging | | |
| Browser | NA | 2.0 XHTML |
| Calendar | | |
| Voicedialing | | |
| IP Code | NA | NA |
| Predictive text | | |
| RSS reader | | |
| Voicememo | | |
| PC Synchronization | | |
| SyncML | | |
| Website | Website | Website |