''Your network provider may charge for SMS messages used to activate iMessage

If you can’t turn on or sign in to iMessage or FaceTime on your iPhone - Apple Support

"If you're using an iPhone, you need SMS messaging to activate your phone number with iMessage and FaceTime. Depending on your carrier, you might be charged for this SMS."

"If a prompt appears stating "Your carrier may charge for SMS messages used to activate FaceTime and iMessage", tap "OK" to allow possible SMS charges."

Note that once you are sending iMessages over the Internet, they might go either over Wi-Fi to an Internet hot-spot, or over cellular data, depending upon what Internet connection(s) you have at the time, and what you let the phone use.

My understanding is that iMessages mostly go over the Internet. But to set up iMessage communication, the phone sometimes needs to send SMS messages (the type that go over the cell phone network).

The dialog is telling you that your phone wants to send a SMS message, as part of setting up iMessage. Depending on your cell phone plan, this might cost nothing – or your carrier might charge you for sending the SMS message.

You have two choices:

• Allow the phone to send the SMS message needed to set up iMessage (and incur the bill, if there is one).
• Tell the phone that it isn't allowed to send that SMS message, in which case you will be unable to use iMessage.

Vanshuarora wrote:

Solve this problem

[Edited by Moderator]

Solve what problem? It's a factual statement. Some carriers will charge for using data, which SMS messages require. If you have unlimited data with your carrier, this message won't apply to you. If you have a metered data plan and you are charged for going over the data limit your plan provides, you may be charged for going over your data limit. That has nothing to do with Apple. All that is being shared with you is a statement you could be charged by your carrier if you go over your data limit, IF you have a data limit.