GrameenPhone 20 Year Celebration Offer! Surprise offer for Grameenphone Customers on 20th birthday! Dial *2020# from Your GP Number or Go to your Message option, type “GP20” and send to 9999. After Successful dialing or sending the message, you will receive a special offer instantly. Example: 2GB Internet 89TK for 7 Days (Dial: *121*3127#). Read more details from the below.