Bharat Sanchar Nigam [BSNL] — Cant send port message to 1900 even with the balance in the account. I can send message to other number but cannot send it to1900

Can’t send port message to 1900 even with the balance in the account. I can send message to other number but cannot send it to 1900. When I called customer care they have rashly replied recharge with 147 to send message to 1900. Why should I spend 147 to leave a service. I have audio proof on the same too.