When someone replies to an SMS sent out of Palace they get a message advising when they reply that they will incur a cost.
They DO NOT Get charged...
This is a generic message for most smart phone text messages to a 'Short Number'.
Palace uses a 'Short Number' service which means all text messages come from a 4 digit number (it's the same service that they use for competitions and txt-a-park etc...). Smart phones generally now recognize that this is not a standard number and know that using the service can allow companies to tack on charges to replies... so a pop up a message usually warning they 'could' be charged for texting to these numbers is shown. The message actually comes from the smart phone and NOT from the service itself. There is not extra charge for replying to those txt message in Palace.