I was unable to backup an existing AT&T GoPhone activation token using:

./iASign.mac --backup atandt.pem

Code:
Waiting for iPhone...
Found iPhone Device: 1
Connection... OK
Could not locate the activation record on the iPhone...
Are you sure your iPhone is activated?
I checked the state using: ./iASign.mac --state

Code:
Waiting for iPhone...
Found iPhone Device: 1
Connection... OK
State: Activated
Any ideas?