To add airtime to your account with an MTS Prepaid Wireless airtime voucher just dial #TALK (#8255) from your cell phone or 1 888 283-1873 from a landline phone. Follow the prompts to enter the PIN found on the voucher.
Or add time using a Visa or MasterCard. Dial #TALK (#8255) or #TIME (#8463) from your cell phone or 1 877 629-8646 from a landline phone. Enter your credit card number and expiry date, select the airtime amount you would like added to your account, and record the transaction number announced at the end of the process.
There are a few more information links here for evolve prepaid