Summer offers the MTS: "I am so HOTyu to" Summer "did not finish-a-alos ..."

Summer offers the MTS: "I am so HOTyu to" Summer "did not finish-a-alos ..." So waited for summer offers. And while MTS 'rolled out' to market a new tariff plan "HOT Jeans for new subscribers and already traditional share Jeans + Summer for the already connected users. I wonder what all the "big three" GSM-operators virtually simultaneously attended to the privacy of their subscribers by offering free or cheap phone calls at night. More than reasonable: at night, the network basically running on empty, so why not let popolzovavshis still disappearing resource? Especially, if by that be able to collect at least some extra money.