i've seen this before, but don't remember where to turn it off. if it's not in the CLID, then check CDP entries in LD 87, although something tells me it's set up in LD 17.
i think the H stands for home, but i could be wrong. these are internal calls, right?
as i'm thinking about this, i don't know if i've ever seen a PRI between PBX's, most companies go w/a TIE line instead.
good luck.