You may wish to do this outside the OBi (by getting a US DID from a VoIP provider and forwarding it to your number in India). This will be a little more expensive, but will pass SMS (not possible with the OBi) and caller ID (difficult with the OBi). Also, if the OBi will be in an unattended location while you are in India, using an external provider may be more reliable.
With Anveo, a Value DID is $0.99/mo.; forward to IN mobile is $0.017 to $0.019/min., depending on carrier. However, the Value DID provides only 40 free incoming minutes per day, with extra usage at $0.015/min., in addition to the outbound rate.
For heavy usage, you might go with Localphone. Their DIDs are $0.99/mo. unlimited; outbound to IN mobile is $0.015/min. IMO, quality and reliability is ok, but inferior to Anveo. Also, they send a 10-digit caller ID, which your phone will likely misinterpret.
If you want to save the cost of a DID and forward in the OBi, be aware that the VGx gateways do not pass caller ID. You could set up SP2 (if you don't need it for anything else) for Flowroute, Voxbeam or Vitelity. With Voxbeam, you must use IP authentication. With Vitelity, IP authentication is optional, but because of limitations in the OBi, it's required if you want caller ID to pass. Flowroute and Voxbeam give you a small credit at signup, so you can test the system without making a payment.
If you forward in the OBi and don't care about the caller ID, you can of course use any desired provider (and configure it as VGx, if you are using SP2 for something else).
