Level 3: Gumshoe

Using a Telstra Smart Modem for Phone Services with an ASUS AC3100 Router

Date: 31-July-2019


This information relates to installing an ASUS DSL AC3100 router directly to a FTTN Telstra NBN connection.  The Telstra Smart Modem (Technicolor DJ A0231TLS) was then connected to the ASUS router to provide telephone services only (no mobile back-up to the internet service).


I could not find simple, step by step instructions but eventually got this set up working.  Every router is different – I will refer to the options on the ASUS AC3100 as a guide only.  Setting the Telstra Smart Modem up behind a “3rd Party” router is a bit tricky because the Telstra Modem sends out a SIP “heartbeat” every 10 minutes.  If it doesn’t get through – it diverts all incoming calls to message bank.


I don’t think it is possible to “break” the Telstra Smart Modem – I had to press the reset button a number of times when I changed a setting that made the modem hard to contact on the network.




Get your Telstra Smart Modem set up and running smoothly.  Check the internet, email applications and phone works.  Follow Telstra’s instructions on how to log onto it – I changed the WiFi network name and password to the “old” name(s) so I didn’t have to re-program every device in the house.  This step is pretty straightforward AND you can phone a friend (well Telstra anyway) if you get stuck.


Turn the WiFi OFF by pressing the button on the back of the Telstra Modem.  Unplug the “phone line” into the Telstra Modem (so you can connect your 3rd Party Modem).  Leave the Telstra Modem plugged into the power.




Get your 3rd Party router connected to the internet.  FTTN is delivered using DSL – so get the correct plug into the DSL socket in the router.


On the ASUS – go to Administration (Left hand menu) then DSL Setting Tab


DSL modulation : VDSL2

ANNEX Mode: Annex A/L/M

SRA (Seamless Rate Adaptation): Enabled

Bitswap: Enabled

VDSL Profile: 17a

G.INP (G.998.4): Enabled

G.vector (G.993.5): Enabled

Stability Adjustment (ADSL): Disabled


Some other settings are on the WAN (Left hand menu) then Internet Connection Tab


DSL / Ethernet: VDSL WAN (PTM)


Under PVC settings:


WAN Connection Type: Automatic IP

Enable WAN: Yes

Default Route: WAN 1

Enable UPnP: Yes

802.1q – Enable: No (some info I found said to turn this on but this stopped the Internet every time I did)


Connect to WAN DNS Server Automatically: Yes

MAC Address: (leave blank)


Go back to the Network Map and click on the Internet Status – it will take a while but it should go from “Initialising” to “Connected” in about 5 minutes.


You should now have working internet / email applications but no phone.




Using an ethernet cable (like the one supplied with the Telstra modem) – connect a LAN port (yellow) on your 3rd Party Router to the WAN port (red) on the Telstra Smart Modem.  Check the Network Map / Clients and the Telstra Modem should appear with an IP address like, might be called “mymodem” and have a DHCP symbol beside it.


Your phone will work for incoming / outgoing calls for 600 seconds – then incoming calls will divert to message bank.  To prevent this – port forwarding for a range of ports must be enabled.




Set the Telstra Modem as a “static” IP address.  This is done on your 3rd Party Router.  On the ASUS – go to the LAN option (Left Hand Menu) then DHCP Server Tab.  There is an option for “Manually Assigned IP around the DHCP list”.  Click on the MAC Address field and “mymodem” should be there – select it.  In the IP address field type in – add then apply.  The last number can be anything between 2 and 254.  DHCP addresses are allocated on a first come, first served based so setting a high number (100) for your Telstra Modem should avoid the dreaded IP Conflict of 2 devices with the same IP addresses on your network.


Go back to the Network Map and check the Clients – the Modem IP address won’t have changed.  Reboot the 3rd Party Router (or turn it off and on).  When it powers back up – the “mymodem” entry should now have the IP address you set and be identified as “STATIC”




Set up port forwarding.  On the ASUS – WAN (Left Hand Menu) then Virtual Server / Port Forwarding.  Under Basic Config – Enable Port Forwarding: Yes, don’t select anything for Famous Server or Famous Game Lists.  In the Port Forwarding List – you can make up a Service Name (Telstra SIP1, 2, 3 etc).  Set the following to the “mymodem” or IP address

Port 5060:5061 Protocol: BOTH

Port 3478 Protocol: BOTH

Port 5004 Protocol: UDP

Ports 10000:20000 Protocol: UDP


Hit Apply.  On the ASUS you can get a report on Port Forward on the System Log (Left Hand Menu) Port Forwarding Tab – it splits out the ports for BOTH as TCP and UDP so the list looks a bit longer.  This is a good check that you have got the Telstra Modem Static IP address AND Port Forwarding working




Nearly there – Disable SIP ALG (whatever that is).  On the ASUS – WAN (Left Hand Menu) then NAT Passthrough Tab.  Choose the SIP Passthrough: DISABLE – all the others can be left enabled.


Great work – have a cup of tea and phone your landline number after 10 or 15 minutes.  If it goes to message bank – something has been missed.


The great thing about this setup is that the Telstra Smart Modem can be uplugged from the 3rd Party Router, plugged into the “phone socket” and the WiFi button turned back on – and it should work perfectly.


I was confused by a lot of posts that indicated you needed to change a lot of settings in the Telstra Smart Modem – you can turn the WiFi off using the control panel but this just makes it a hassle to turn back on.


I hope this information saves someone the few hours of fumbling through things that I had to waste.

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