[asterisk-users] A question about Caller ID

[Christian]

Hi all,
Sorry if this is a little off topic, but I just want to know a thing here.
What system is used for sending out the caller's number in the US?
Here in Sweden we use DTMF to send the number out. I just need to know what is used in the US since I don't think I will be able to use an American caller ID device over here.
Many thanks for any info,
Christian