Idea Cellular — Unable to send port message to 1900 from Idea Cellular Number

Dear Team,
I have been trying to send a port message to 1900 from my idea number +[protected] by using format port SMS. However the messages are not being sent, it shows sending failed every time. I have tested sending messages to other numbers and it works but messages sent to 1900 are being blocked. I have talked to idea customer care who repeatedly states that they couldn't find any reasons why port messages wouldn't be delivered.

Kindly do the needful for the same.

Thanks and regards
Abu Bakkar Siddique