Tata Docomo — tata docomo unable to send sms to 1900 (porting number)

Address:

Whitefield, 560066

I can't send sms on 1900. I have sufficient balance and nothing is due on me. I have prepaid no.

Every thing is ok as calling and sending sms on other numbers works well.

Only when I am sending SMS to 1900 for Porting the message states.

You don't have sufficient balance to send this SMS

I tried to call costomer care and still ivr tells for busy.
Kindly resolve it as asoon as possible