They might also charge more or less depending on the time you are calling. You might be required to pay a fee for special access to some of the files, doors, or conferences. However it is worked, the charges are most easily billed to your credit card. When you are choosing an online service, you will need to do a little research. You should make a note of the things you are looking for in an online information service.
Many online services offer starter kits for new users.
The starter kits offer a variety of things to you. It will include registration information, tutorials, users guide and several other useful items available. If you can't decide on a service, then just sign up for one that sounds interesting to you. If it isn't, then quit that one and try another one. It won't take long until you find the one that suits you best.