If you have pages on your site where you cram a whole bunch of phone numbers onto a page, you may want to think twice, because Google will basically get you for keyword stuffing (which is of course, against Google's quality guidelines).
"I wanted to clarify a quick point: when people search for a phone number and land on a page like the one below, it's not really useful and a bad user experience. Also, we do consider it to be keyword stuffing to put so many phone numbers on a page," he said. "There are a few websites that provide value-add for some phone numbers, e.g. sites that let people discuss a specific phone number that keeps calling them over and over. But if a site stuffs a large number of numbers on its pages without substantial value-add, that can violate our guidelines, not to mention annoy users.
Here's the image he refers to:
Cutts added in the comments section, that "these pages have always been considered violations of our guidelines as keywords stuffing - I just wanted to be especially clear so that we could point to explicit guidance we've given."
"Excellent. Now, if you can get Tom with Home Protection to stop robo-pitching us all 3 times a day, that would be superb!" Rob Beschizza said in the comments.
To this, Cutts replied, "You might consider Google Voice to block robocallers. Newer Panasonic cordless phones also let you save a number as blocked."
In case you're unfamiliar with Keyword Stuffing or Google's exact wording, there is a page here that explains it, where it's described as the practice of loading a page with keywords in an attempt to manipulate a site's ranking.