I believe Jumbo Ticket should consider this. There are more ways to prevent abuse of the bonus. But most users here don't like to get KYCed.
Though most of us hate KYC yet if this will be the safest way to gamble and with Phone verification only i believe that this can be given as there are multiple availability of Phone number from place.
Sim card is very cheap in some country, especially on 3rd world country which only cost around 0.2$ each so if this is there only safety measure to counter bonus abuse then many abusers can bypass this and benefits on multiple accounts. Many trusted casinos is only checking IP to detect abuser and it's easy to pinpoint because only a few players can manage to clear the wagering requirements of the bonus while it's easy to very the IP of that particular person.
No one wants to KYC during the registration process because the newcomers still didn't have a chance to experience the casino in able for them to decide if they will will continue even with KYC or not.