As delnan said, if you want all calls ever, it's impossible without a global, so I'm assuming you just want the call depth, for which you just need to add a return value
def f(n):
if n == 1:
return 1,0
else:
x, call_depth= f(n-1)
return n * x, call_depth+1
If you're dealing with several recursive calls, you can do a max(call_depth1, call_depth2)
(depth of longest call tree) or just sum the two (total number of actual calls)