See this and give your comments..
Some more helpful points can be:
Add this source to sources:
touchmods.net/rep.xml
- Add the source touchmods.net/rep.xml to sources.
- Refresh sources and go to install in installer.
- Scroll down to Touchmods and open folder.
- Install Sip-Voip.
- When done installing, finally, restart your iPod.