Hi there! @ww99603 thanks for posting your question. There are no fees to activate your GoPhone service online at https://www.wireless.att.com/GoPhoneWeb/goPhoneLanding.do?method=activatePayGo
Keep in mind since Cellular World is a 3rd party provider of phones and services separate from AT&T, they may charge additional fees for service activations and even payments.
Hope this helps!
Charise