I don't know this for
> sure, but I'm guessing changing the name of a big company might be
> really expensive but using another name for the business might be as
> easy as filing a form with a state's corporation commission.
That is true.
But in the case of Verizon, I'm reasonably sure they did indeed legally change their name (IIRC, the newspapers said it was voted on a the Annual Meeting of the stockholders); and that included changing the local units' names.
This same syndrome afflicts many railroads; One road buys another,
> paints new logos all over everything but retains the old name on
> deeds to properties, operating authorities and the like.
Railroads often don't directly own all the tracks and routes. Some are on long term leases where the owner gets rent check every year. Others are wholly owned but under a separate name. (AT&T had a "195 Corporation" which just dealt with its HQ bldg).
In the case of Verizon and prior Bell names, I suspect the other poster who said it was for trademark protection was correct. I notice black Verizon pay phones have the Bell logo on the side.
One other possibility of printing a legacy name on ads is to distinguish the Bell side from the GTE side. I suspect former GTE customers will use legacy GTE services and plans for quite some time to come. (Any former GTE customers now on Verizon want to comment on this issue?)
The holder of the Pennsylvania Railroad trademark apparently let it lapse. Some smart private guy quickly snapped it up, then demanded royalties from all the model makers and publishers who use the PRR logo. It got kind of messy and I don't know the details, but the original holder (a corporate descendent) got the rights back. Other railroads are a little more careful with their logos. They don't usually charge modelers for their use, but they don't let them lapse either.
[TELECOM Digest Editor's Note: The same thing happened with the internet-history.org URL. It accidentally got away and the person who cybersquats on it now are demanding big ransom for its return. He'll have to wait a bit longer before I give him anything. PAT]