There is a manual
web recovery mode
We don't have the admin pass and the device is running ancient firmware anyway, lets update to the latest (at the time of writing)
Hold '1' and '#' key while booting the unit. After some time it will get a dhcp address and will jump into web-recovery mode.
Go to the address in the screen:
The default user and pass are Admin/22222
You can now start configuring the device for your voip setup.
For Asterisk (like @ space)
Go to Global SIP: