https://www.prepaidphonenews.com/2019/01/new-customers-get-to-enjoy-double-data.html
According to its announcement, Tello's Double Data promotion is available for new customers who activate service under one of their phone plans. The phone plans available under the promotion include the following options:
$13 per month plan - comes with 1GB of 4G LTE data for six months (originally 500MB)
$14 per month plan - comes with 2GB Of 4G LTE data for six months (originally 1GB)
$19 per month plan - comes with 4GB of 4G LTE data for six months (originally 2GB)
$24 per month plan - comes with 6GB of 4G LTE data for six months (originally 3GB)
$29 per month plan - comes with 8GB of 4G LTE data for six months (originally 4GB)
$39 per month plan - comes with 20GB of 4G LTE data for six months (originally 10GB)
The deal here is that you have to stay under the same plan for six months so you can enjoy double data. If you decide to change the phone plan, the offer will no longer be available.
Again, this promotion is available from January 10-16, 2019.
Just make sure you port in the beginning of the week, not Friday night. 