In theory, yes.
When a call is made there is open channel communication between both parties. If a channel encryption is used then it will be used at both ends in the same respect. So if you were to intercept a call you would either have it all, or nothing.
I see the area for confusion, and I guess it depends on how and where a call is intercepted and received. If you were to intercept a cell transmission the same way you would receive radio packets (i.e. in the same vicinity) then it stands to reason this information would be one way only, however I'd make the assumption that standard cell phones do not make hops mid-call and thus once you have the correct signal address you would get both incoming and outgoing messages (both ends of the call) on the same frequency.
Of course, I am not a technical engineer in such subjects, and this is my 'educated guess' only. I'm sure a short piece of research into the matter would wield some conclusive results.