Few companies over a certain size run their own call centers. It's no different from a software startup using AWS or Rackspace instead of building a server room in their rented office space. I think it is both acceptable and desirable for my phone to tell me Comcast is calling me (as they currently do), even though it's technically an outsourced call center that makes/takes calls for several different companies from the same building and same set of phone numbers. Requiring caller ID match the billing address for the phone number would be like requiring Hacker News be hosted on a cloudflare.com subdomain because the IP space we're talking to isn't actually owned by YC.