Humble and honorific aren’t about who you’re speaking to but rather who you’re speaking about. And you don’t have one particular in-group either: If you’re talking to a friend then your in-group is probably just you, if you’re talking to a stranger then it’s you, your family, your company etc. I think of the in-group as more or less “the people that are closer to me socially than the person I am talking to right now”.
So if you’re speaking politely and you’re talking about someone in your in-group you use humble forms, and if you’re speaking about someone in your out-group you use honorific language. Example dialogue from a textbook:
A: Nakamura-san irassyaimasu ka?
B: Ima tyotto orimasen ga…
A: Zyaa, Nisida-san wa?
B: Nisida desu ka? Nisida wa san-gai ni orimasu ga…
(from Japanse: The Spoken Language Part 1)
Is Mr/s. Nakamura here?
They aren’t here now, but… (would anyone else do?)
How about Mr/s. Nishida?
Nishida? Nishida is on the third floor, but… (is there anything I can do?)
Here both Nakamura and Nishida are people of B’s company, while A is an outsider. And so even if they’re hierarchically above B, B uses humble language to refer to them and doesn’t use honorifics with their names, because in this context, they’re in B’s in-group and B uses the humble verb おる. A on the other hand uses the honorific いらっしゃる when asking about Nakamura, because they’re in A’s out-group.