Include phone number on letters to IRS?

[shopgirl1]

I have read internet postings recommending that phone numbers be omitted from tax returns or written correspondence with the IRS.

However, I still have yet to hear of the IRS calling people.

The internet postings that I read suggested not to include phone numbers because the IRS had previously called certain individuals, left cryptic messages that were undecipherable. Taxpayers called IRS but couldn't make heads nor tails of the request left on their voicemail. Then received penalty letters.

Is this an internet hoax or sound advice?