Let's just say, there's a reason the title that SMNs get after completing the level 70 job quest is "The First Caller".
Level 60-70 SMN quest-line spoilers:
In the level 60 to 70 quest line for SMNs, the Immortal Flames sets up its first unit of summoners, comprising a trio of soldiers who survived at least one encounter with Ifrit, and are thus able to summon Ifrit-egi.
The highest-ranking of the three is also a former member of the Company of Heroes that defeated Titan back in the day, so he's only the second current summoner in Eorzea capable of summoning more than one egi.
I would strongly suggest that the thread starter consult the job trainer, Y'mhitra. She provides the lore for the job right from the beginning. It's not hard to learn the background for the job on your own.