func handler(c twilio.Context) { o := c.IntValue("Offset") if o < 0 || o >= len(digits) { c.Hangup() return } d := "" if o == 0 { d = "3 point " } d += digits[o] c.Responsef(` <Say>%v</Say> <Redirect method="GET">http://pi-phone.appspot.com/?Offset=%v</Redirect> `, d, o+1) }