Replying to Do you need to add a 1 in front of a number?

Got a number and entered a 1 in front of the area code without a +. So the contact looked like 1 (xxx)xxx-xxxx. Sent an imessage from my phone to another iphone and it did say that the message was delivered. Just realized now that most of my contacts don't have a 1 in front of the area code, and if it does, it's a +1. Just wondering if the message never went through because of the 1 I added in front of the number.