Can I use my Visa Gift card for online or phone purchases?
Yes. However, to make an online or phone purchase, you will need to register your card. You can do this by either calling the issuer, or by visiting their web site.

When you make an online or phone purchase, the name, address, and phone number you use will need to be exactly the same as the information you provided when registering your card. If the information is different, the transaction may be declined.

You can verify or update your information by visiting the card provider's web site, or by contacting them using the toll-free number provided in your card documentation.

Remember, that to remain anonymous, many people provide incorrect information when registering their prepaid cards. This does not seem to be a problem in any way, but it is important to remember to provide that same information when using the card for online purchaes.

How do I learn the value of my Visa Gift card?
The initial value of your card should be included in the materials that came with your card. Most issuers also offer web site access, a toll-free number, or instructions on the back of the card.

It is important to know the remaining balance before making a purchase, as making a purchase for an amount greater than your balance could result in a denied transaction.
When making a purchase, record the amount and make a note of your new balance.

Also note that many issuers charge a small fee for using the card. This may be applied per purchase or monthly. Check with the issuer to determine their fees, or to be safe, buy a card with a balance of at least few dollars more than you need for your online purchase do avoid having the card declined for insufficient funds.