Does the traveler shorten the prayer if the call to prayer is made before the journey?

Question:
If a traveler is called to prayer while he is inside the city and he intends to travel, is he permitted to shorten the prayer?

Answer:
He may travel and pray it while traveling. If the call for the midday prayer is made and he leaves, he prays it shortened while traveling. The criterion is the time of the act. Or if he entered the city, entered his hometown, and did not pray, he prays it as four rak'ahs, even if the time for the prayer is present while he is traveling. If the time for the midday prayer comes upon him while he is traveling, but he has entered [the city] without having prayed, he prays it in his hometown as four rak'ahs. Or if the call is made while he is in the town and then he leaves, he prays it as two rak'ahs while traveling.
Q: So the criterion is the time of performance?
A: The time of the act.
Q: Like one who remembered a prayer of the traveler while in a state of non-travel?
A: He prays it as four rak'ahs. The excuse has ceased.