Maybe you recharged your account for the first time? Trying to get outgoing transactional SMS's working? Maybe, you tried to send a test SMS but that does not appear to work?
1) Now that you have made the first payment, Ensure you have purchased an Exophone rather than trying to use the Trial account (free) number. Start here: http://my.exotel.in/numbers
3) If you are sending from the dashboard, then read http://support.exotel.in/support/solutions/articles/56992-why-has-my-sms-not-reached-the-recipient-when-will-it-reach-