Tello $10 Free Referral Signup Bonus Credit. 

Account Credit is provided after you purchase new service Nothing will be mailed, shipped or picked up, no SIM card or anything.

put the Referral Code:  P30GD2D5 in the space provided as in the SECOND picture.

To get your one time $10 credit: 

Referral Code:  P30GD2D5