I have just bought a Sipura SPA-3000 from ebay, 20 Euros. If I could wait I think I could buy it some 5 Euros cheaper.
Here are the initial steps for its configuration:
1. Connect Lan port of spa 3000 to the router, phone to a phone and line to PSTN line.
2. Using the connected phone, press 4 times *. The voice menu will be played.
3. press 111 to set static address, 121 to set network mask
4. you should be able to access its website. You can set DNS
5. I could easily connect to my jumblo and 1und1 account with these settings: Here I bring 1und1 settings:
6. in line1 menu:
Make Call Without Reg: yes
Ans Call Without Reg: yes
Register Expires: 3600
Display Name: name
USer ID: 49xxxxxxxxxxx
in SIP advanced menu, in NAT Support Parameters:
STUN enable: yes
STUN server: stun.1und1.de
that is it, next time I restart it, I can see in info that Line1 is registered and I can call from and call to it.