Radio Timeslot requests may be blocked due to an overlap with activities already scheduled by the SoftDevice.
Figure 1 shows a situation in the middle of a session where a requested timeslot cannot be scheduled. At the end of the first timeslot illustrated here, the application signal handler returns a REQUEST_AND_END action to request a new timeslot. The new timeslot cannot be scheduled as requested, because of a collision with an already scheduled SoftDevice activity. The application is notified about this by a BLOCKED event to the application event handler. The application then makes a new request for a later point in time. This request succeeds (it does not collide with anything), and a new timeslot is eventually scheduled.