This is not a "hot deal" but rather solution for techies.
Zoom 5801 VoIP device got interesting feature - PSTN passthrough.
Imagine that you have mobile phone with a lot of inclusive minutes. In this case you can configure Zoom 5801 to make international calls from your mobile at VoIP prices.
Here is how it works:
1. Dial your home phone number
2. Zoom answers the call (special dial tone I guess).
3. Dial access password.
4. Get dial tone
5. Make call.
Your mobile provider will charge you as a normal landline call and your VoIP provider will charge you as an international call. This should be much cheaper than dialling international numbers from your mobile.
I haven't tried it myself (yet) as it took me almost whole day just to get dang thing to work at all. But it should be possible with some effort :)