Summarizing what I've gathered from numerous sources...The purpose of the hourly satellite-to-plane "handshakes" is to allow the satellite to know the approximate location of the aircraft so that it can transmit any messages. For this, the satellite needs to know the angle of the aircraft from the satellite. The satellite is around 22,000 miles in orbit, west of center of the Indean Ocean at the final "ping" moment, 8:11am.
An aircraft directly under the satellite would be at a 90 degree angle to the satellite and an aircraft at the poles would be at 0 degrees.
In the case of Malaysia Airlines 370, authorities have said, the last message sent was at 40 degrees. Satellite and accident investigation experts have used that information to determine the possible location of the plane, somewhere in the vicinity of those red lines spanning from Northern Thailand to Southern Kazakhastan, or southern Indonesia to southern Indean Ocean.
If this information is correct and the satellite ping indication of the plane being at 40 degrees from it is correct, how can the plane be anywhere near Iran or adjacent middle east countries? Could it have landed somewhere, refueled, and flown to the area of one of the red lines within that time frame? I'm focused more on the northern red line, as the southern red line may point more towards intentional ditching at sea or pilot suicide as others have mentioned.
I have my reservations until more concrete evidence is found, but this is what we have to work with at this point.