Need Text Msg Auto-Reply

I am going to be out of the country for 3 weeks and leaving my work iPhone at home so I don't get HUGE roaming charges.

Clients often text me to see if I'm available. Is there a way to have an auto reply go back to all texts that come in while I'm gone so people don't think I've gone out of business?

Last time I took my client phone with me out of the country my bill was INSANE. Would rather have them simply get an auto-reply saying: "I'm on vacation out of the country and will be back on November 17".