Taking your statements at face value, it seems unlikely that Vonage has anything to do with it since you said you gave them a credit card number. If, however, it wasn't actually a credit card, but instead one of those debit cards that looks-and-feels like a credit card (what do you call those? Checking cards? We don't really have those here in Canada...), then it's quite possible that the charges from Vonage contributed.
The lesson learned here is to always be aware of about how much should be in your account. I actually log into my online banking just about every day, just to keep tabs -- both to remind myself how much is in there, and double check when things are added or disappear. Pay gets deposited every other week, and every month a number of things automatically disappear -- money for my car lease, auto insurance, and now home insurance and mortgage. The fun part is how they all leave my account at different times of the month, so I have to get used to watching the numbers and making sure that the money's there when it needs to be. If I slip up, then I need to quickly transfer over some money temporarily from my savings account.
The alternative is to keep enough money in there that you'll know you always have something, but then that's money that isn't earning higher interest in an investment savings account, or money not being used to buy a new MacBook Pro
For example, my first mortgage payment is scheduled to disappear from my account in the next two days or so. My next payday is this coming Friday. So I need to make sure I don't buy anything big for the next few days. It's not strictly how much you have, it's when you'll have it, too!
