When using the UC dial plans did you use the part to include your local extension range ?
Things to consider also are if you need team's users to dial other system numbers, i.e service flags or pbx ring groups, your dial plan needs to accommodate that.
Typically, if 2 users are on teams they just use teams <-> teams to call each other, not the extension digits/pbx.
I find the best way to think of it is using it like as if you were pairing a mobile number to the extension, teams is really just another end device, with limited PBX functions, like a mobile.