Technically, yes. However, a lot of this falls to what the DM will allow. Given what you've already said, it seems your DM would be open to back-dooring interactions with powerful outsiders for the sake of story.
Back in AD&D it was heavily implied that learning and speaking the true names of greater Devils and Demons would get their attention. Usually they would show up to eliminate whosoever spoke their name, as knowledge of a true name grants a minute amount of power over the creature. However once you had their attention it was possible to bargain with these creatures by trading wealth or favours.
If your DM has supplied you with a setting containing ancient libraries or the like, you may be able to research the true names of such creatures. This would require a Knowledge check, and would probably be a DC 20-or-30-something and take a lot of time:
Equipment (Library) If you have access to an extensive library that covers a specific skill, this limit [on the DC of untrained checks] is removed. The time to make checks using a library, however, increases to 1d4 hours. Particularly complete libraries might even grant a bonus on Knowledge checks in the fields that they cover.
Slight anecdotal aside - A friend of mine was in a campaign where one of his party members accidentally summoned a Greater Vrock. The components of a summoning ritual were already set up in an abandoned church. By completing the ritual for s/hts and giggles, he summoned a Greater Vrock and ended up in some kind of obscure soul-bound contract with it. By this example your DM could work in extraplanar contact as part of the setting/story and not have to be so tightly bound by RAW.