When do those who intend to pray in the last part of its time call the adhan?

Q: A question from: A. S. H. — He says: If we are a group and we intend to pray, for example, in the last part of the time for the Zuhr prayer, is it obligatory to call the adhan at the beginning of the time or at the end? And is our prayer valid without an adhan?

A: If you are in a town, it is obligatory for you to pray with the Muslims in the mosques, except for one who has an excuse such as illness. And if one prays at home for a valid legal excuse, the adhan of the people of the town suffices for him, and it is prescribed that he call the iqamah for the prayer.
As for if you are in the desert, it is obligatory for you to call the adhan and the iqamah; because the adhan and the iqamah are a collective obligation in the most correct of the two opinions of the scholars; due to the saying of the Prophet (peace and blessings be upon him) to Malik ibn al-Huwayrith and his companions: And in another wording: He said to him and his companion: And because he (peace and blessings be upon him) ordered Bilal to call the adhan in Madinah, and ordered Abu Mahdhurah to call the adhan in Makkah, and ordered both of them to call the iqamah. And he (peace and blessings be upon him) did not cease to perform the five prayers in Madinah with an adhan and an iqamah, so that indicates their obligation. And due to his (peace and blessings be upon him) saying: .
As for calling the adhan at the beginning of the time — if you are in the desert — or at the end of it, the matter is broad in that, if Allah wills.
And the best is to hasten with the adhan and the prayer at the beginning of the time. And if you delay the adhan and the prayer and combine the Zuhr with the 'Asr, and the Maghrib with the 'Isha', there is no harm in the state of travel; because the traveler has the right to combine in travel, combining by delay and combining by advance, according to what is more convenient for him. And if he is on a moving vehicle, the best for him is to delay the Zuhr until the 'Asr if he departs before the sun reaches its zenith, and the Maghrib until the 'Isha' if he departs before sunset. But if he departs after the sun reaches its zenith, the best is to advance the 'Asr with the Zuhr. And likewise, if he departs after sunset, the best is to advance the 'Isha' with the Maghrib; because what indicates that has been authentically reported from the Prophet (peace and blessings be upon him). And Allah (Glorified and Exalted is He) said: : [Al-Ahzab: 21]. And he (peace and blessings be upon him) said: Narrated by al-Bukhari and Muslim. And success is from Allah.