I strongly suggest you do not use Telstra's Voice Extender. I used this device with two Telstra Smart Modem Generation 2 modems and it is problematic. Regularly disconnecting its connection to the modem and disrupting other wifi devices connected to the modem causing them to unpair. This problem occurred every 3 days or so. Once removed and not used all the problems went away and never returned. Telstra re-credited my account $48 as I returned the device to a Telstra store. Instead get a phone point installed by an electrician that will give you a hard wired connection to the modem from that phone point (can be anywhere in your home). Should cost about $90>$100 for an electrician. The Voice Extender also had an issue with loud crackling radio interference sounds from time to time...it is a no joy device for sure.