Step 1
Open your iPhone’s Settings. Check the Utilities folder if you don’t see it.

Step 2
Scroll down and tap on "General". You may have to scroll down 1 or 2 screens to find it.

Step 3
Tap on "About".

Step 4
Scroll down and tap "SEID". You will find it near the bottom of the list.

Step 5
Long press the SEID and click on "Copy".
