The Lumia 638 is a variant of the Lumia 635 with India's widely used & supported TDD-LTE bands.
It's other main Specs are:
- Main camera: 5.0MP
- Display size: 4.5''
- Display resolution: FWVGA (854 x 480)
- Battery capacity: 1830mAh
- Processor name: Snapdragon™ 400
- Processor type: Quad-core 1.2GHz
- Mass memory: 8GB
Microsoft is really going all out in its efforts to dominate the low end market.
Check out more on this device on its Products Page