Tata Docomo — unable to send message to 1900 to port my sim

I want to port my number from docomo to airtel. For that when i tried to send message to 1900, the message was blocked from being sent, despite having sufficient balance in my phone. I m able to send msg to other numbers without any hindrance. Also my internet connection is not working for the past 3 days. Please help me resolve the problem as soon as possible.