Starting June 21st, AT&T is officially adding LTE 4G support and a new set of plans to its GoPhone prepaid network. The base tier costs $25 per month, and includes unlimited texting and 250 voice minutes, but no data unless a person pays an extra $5 for 50MB. With a $40 plan people can upgrade to 500 minutes and 200MB of data, expandable to 300MB for $5.