Never use your main email if possible.
Use one of your legit 'web-mails'. Yahoo, lycos, excite for entrance.
All they care about is a way to contact you for whatever reason.
Far as phone number goes.
Most those folks don't like spam in their emails either.
Bet a large percentage of the phone numbers they get are bogus and they know it plus understand why.
Do you really think they'll use the phone source as a first choice too contact you?
Yo Mr. Owner (bossman)! I'm going to ring up your phone bill [doesn't matter if they have access to an 800 no# etc etc. They still have an allotment per month] because I don't want to go the email road.
It is all write offs but if they can, they'll go the easiest path.
Most cases, I doubt if it matters one way or another though.
They give out a customers info ... they're cutting off there own bread and butter.
Bad business practice.
Now if you are really, really worried about handing out your landline number.
Just give them
Rob Ws number.