I figured it out. It was a long process but it works.
For the man in the phone booth I used little reverb, some panning, muffled engine sounds and a faint whisper of wind coming in and out (to simulate wind coming through the phone booth opening)
For the vox on the other end of the phone(while still in the phonebooth) I simply used a portable tape recorder with a mic. I put the recorder in the backseat of my ride, started recording and talking and it came out perfect.
so the result was something like this:
Man in Motel talking to subject in Phone booth (no special processing)
Phonebooth man listening to instructions from man in motel (ambience + vox recorded from tape)
Phonebooth man speaking (ambience + reverb)
Now I can try some straight eq to smooth and clean it all out.