Be sure you are using a touch-tone phone. If you have trouble dialing the destination number, please check that you are using a touch-tone phone. To check if your phone is set to pulse or tone, pick up your phone and press any button. If you hear a tone when you are pressing the button, your telephone is set to tone dial. If you hear clicking, it is set to pulse dial.
Many phones have a little switch which can change between tone and pulse.
Switch it to tone and try again. If you don't have a touch-tone phone, you can purchase a tone generator from an electronics store. Call your Trigger Number. However, instead of hanging up after one ring, let the number ring until answered. Thereafter, key your 4-digit PIN number to enter the system.