Next Call logic:
First get Customer who is currently locked for this Agent with no result (attempted in the last 30 minutes)
Agent clicked the "Next Call" link and opened the call screen for this customer
No result was recorded
Call incomplete
"Lock" lasts for 30 minutes
Second get Customers who haven't been attempted
Customer has NOT yet appeared in the call screen when the "Next Call" link was clicked
Lastly, get Customers who have been attempted (but not in the last 30 minutes)
Customer has appeared in the call screen when the "Next Call" link was clicked
A result has been recorded, but not a result that completes the call
This customer will only appear for the agent that originally opened the call screen with the customer
30 minutes must elapse from the last time the call was attempted
If a customer is not returned or the customer returned is in the locked status (step 1), the "There are no more calls to make right now." will be displayed.