If your telephone service is to be provided over the UNID port of your NBN service, or if you have Fibre to the Node & the telephone service is being provided over the data connection, these are the settings you need to set in your ATA.
The ATA (Analogue telephone Adaptor) is the device that allows you to connect a regular phone handset to your connection to make & receive calls.
It may be built into your modem/router, or it may be a separate device connected to your modem/ router.
Username: As we specify. It will normally be a number starting with 600 followed by @univ.rivertel.com.au
Password: As you specified
Proxy: (might also be called server) sip.wireline.com.au