Try this: -
"Hi - can you put me through to John?"
"Who is it please?"
"Err...right OK - let me transfer you."
Use quite a flat voice, almost a monotone.
I'm always amazed how often this works.
If you answer the question with your company name you'll sound like every other salesperson.
Naming your city makes you sound different. You sound familiar.
And you haven't said anything false - you've just been selective in the information you're sharing to make your job easier.