I was getting the same error message. I sent an email to their support department. They informed me that my phone number is not registered and asked me to try again. I did and I was still getting the same message. I read their mail again and I saw their warning message asking me NOT to enter the + sign before the number. I did and it worked. Please make sure that you enter your number as 9198XXXXXXXX.

Answered by Rishoo Singh , an ibibo Advisor, at 2:20 AM on July 01, 2008