Having trouble sending SMS to India

Hi,
I am using the SIM808 FONA shield from Adafruit along with Arduino. I am using the FONA test program example. I am residing in the US, however, I am planning to send an SMS to India. I am unable to send. I tried adding the prefix “91” and “+91” still couldn’t send. Should I enable anything specific in Hologram to enable messaging to India from the US.

Eventually, this board will be used in India, where they have to receive messages. Will there be a hickup?

One thing to note is, SIM808 is 2G module.