Delays when making and receiving call are separate issues though some of the causes may be the same.
1. When calling there may be unnecessary delay, perhaps as much as 10 seconds, incurred if the dial plan in your OBi is not optimal. Any more than that is down to your ITSP, route selection and the callee's ITSP.
2. When someone calls you there may be delays in their dial plan, their ITSP, route selection, and your ITSP. And if it is a POTS line coming into an OBi110, the Ring Delay set on the 110.