I have investigated this issue of OpenTable using a Premium Rate phone line to send booking details and ask for booking status conformations. You will be charged if you respond to their booking reminders or send the STOP to opt out of their reminder service. Open Table claim they don't get the fee but BT who charge me £0.13 per SMS Text, insist they pay the money to OpenTable. The Phone Paid Service Authority who are supposed to regulate this confirm OpenTable does use a premium rate line and should warn customers that they will be charged.
