telnetd an
I bought a Fritz!Box 7050 for cheap on eBay the other day. It's a home router with built-in DSL modem, WLAN, and a POTS interface. The reason I got it was that I'd like to ditch my aging, bulky, and increasingly flaky ISDN phone in favour of using my mobile as a VOIP handset for the Fritz!Box.
The device itself works very well, including my old phone, WLAN, and ADSL2+. Unfortunately, as it turns out, the 7050 doesn't support VOIP handsets in the stock firmware. Google says, however, that you can actually run full-blown Asterisk on it. Now, the reason for this post is my amusement over the method to get a shell on the thing. Connect a phone, dial #96*7*, et voila:

A lot of frustrating frickel later, however, I've decided to give up for today. I got Asterisk to run, dialing out from the PC via X-Lite actually worked, but SIP registration fails on my Nokia E51, for unknown reasons.
For later reference, here's the list of the relevant links I found:
- http://www.avm.de/de/Service/Service-Portale/Service-Portal/index.php?portal=FRITZ!Box_Fon_WLAN_7050
- http://www.juerging.net/projekte/Fritzbox-Asterisk/
- http://www.wehavemorefun.de/fritzbox/Hilfsprogramme_/_Tipps_&_Tricks#Asterisk_.28capi_intern.2Bextern.2Fiax2.2Fsip.29_auf_der_7050_.28ohne_Firmware-Mod.29
- http://www.asterisk-kompakt.de/artikel/45-asterisk-auf-fritzbox-phone.html
- http://www.spblinux.de/fbox/info/asterisk/sip.conf.default
- http://nuxx.net/blog/2008/10/24/sip-via-asterisk-on-nokia-e51/
- http://www.ip-phone-forum.de/showthread.php?t=161714