Verizon has sent notices to FiOS customers who are using the company's oldest type of high-definition set-top boxes: As of April 15, certain HD channels will no longer be accessible using those boxes. Customers who want to view the channels will have to exchange the old box for a new one, but there's no charge for doing so.

Customers do not have to exchange their older set-top boxes. If someone keeps the older box and tunes to one of the affected channels on or after April 15, a message will appear onscreen with instructions on how to exchange boxes.

A Verizon spokesman told us that any recorded content on returned boxes would be lost--there's no way to transfer it to a new box. But any purchased content would still be accessible from the new box.

Wondering how your TV service stacks up? Our 2013 television service Ratings will be released at the end of March.

To find out if your FiOS box is affected, press the Menu button on your remote, navigate to Customer Support, select In-Home Agent, choose Set Top Box Exchange, press OK, and follow the prompts.

The affected channels are:ES.TV

ESPN Goal Line/Buzzer Beater

Tennis Channel

World Fishing Network

Cars.TV

Pets.TV

MyDestination.TV

Recipe.TV

Comedy.TV

HBO Family

HBO Family (West)

HBO Latino

HBO Latino West

MoreMax (West)

Action Max

Thriller Max

W Max

At Max