Unbundled VoIP with Long Distance

I've been looking into how to make Voice over IP calls from a Macintosh with a good VoIP software client without being tied into a specific service. Most of the Mac clients I've tried are fairly poor. The Xten X-Lite and X-Pro clients are fairly fantastic to use (though annoying to configure), and they have Lindows (now Linspire), Windows, Mac, and Pocket PC clients. The X-Pro client is particularly interesting because you can conference up to six VoIP lines.The tricky part is that Xten makes the client but they don't resell service. It's a standard SIP client, so if you can find a long-distance provider that provides its SIP gateway settings, you should conceivably be able to use the best client with an affordable long distance service. I found that iConnectHere, part of Delta Three, offers inexpensive long distance (about 3.5 cents per minute for continental US long distance, no monthly fee; lower rates with small monthly fees) -- and they provide details on using their SIP gateway from another VoIP soft phone or hardware adapter. I still think that Apple needs to modify iChat to allow voice calls through a long-distance partner. I've already got the software; it already supports SIP and voice over IP. Just add a gateway option or let me configure it myself, and iChat becomes iPhone.