No Caller ID does not necessarily mean you have the person in your contacts. The term generally refers to a situation in which the caller's information is withheld from the call's recipient. There are several reasons someone would make a call without revealing their identity, and it's not always because they're trying to hide something. In some cases, No Caller ID calls are simply convenient. For example, if you're calling someone you know but don't have their number stored in your phone, you might make the call without revealing your caller ID. This way, they won't have your number stored in their phone either, and you can avoid any potential awkwardness from them knowing your number but not vice versa.