There could be a few reasons for this.
1. Is your number switched "ON" in the Exotel dashboard?
Even if you're logged in to http://my.exotel.in, you need to be switched on to receive calls. You can check this on the top right corner of your account.
2. Are a part of the group that is configured to receive calls?
For example, if the group Exotel Employees is set to receive calls as a part of your incoming call flow, check if you're a part of the group. Go the Co-workers & Groups page and check the group by clicking on it. If not, adding yourself to the group by dragging and dropping your name to the group.
3. Momentary issues
There could be momentary issues at the operator's end. Give it a few minutes and try again. If it's still not fixed, get in touch with your account manager by clicking on the Support tab at the bottom of your account.