Is it obligatory for someone praying alone, due to the absence of a mosque, to say the Adhan and Iqamah, or is it permissible for him to pray without the Adhan or Iqamah?

The Adhan (call to prayer) and Iqamah (second call to prayer) are Sunnah, and their obligation is a matter of scholarly disagreement. However, it is more cautious to perform them. It is incumbent upon the worshiper to pray in congregation whenever possible. If he hears the call or finds a nearby mosque, he must answer the call and attend with the congregation. Otherwise, it is Sunnah for him to make the Adhan and Iqamah by himself.