It has a Panasonic KX-TDA5161 4-Port Doorphone/Door Opener Card (DPH4) installed. It is currently being used to open a electric gate. When visitors come to the gate and press the Viking intercom, anyone in the house that answers can open the gate by pressing 5. They can also open the gate by using the *5501 feature. The client would love to be able to open the gate from her cell phone. Any ideas ?