[Serusers] SIP Service Providers supporting Windows Messenger 4.6

Hi, Reading the SERusers digest for a few months has allowed me to read about a lot of very complex and specialized problems. It's a bit intimidating. Although I might some day want to learn to administer a Linux system and run my own SER server, at this point I would rather just become a paying customer on someone else's SER server. Many of the list participants are clearly professionals operating large SIP service providers. But none of these professionals have identified their organizations clearly enough to let me become their customer. Perhaps because the traditions of the list prohibit users from advertising their commercial services. Can someone please give me a recommendation of a SIP service provider which has good service and reasonable pricing. I need a service which will allow me to call between two computers, each running Windows Messenger 4.6/4.7 . I am aware that the latest version, Windows Messenger 5.1 does not allow connecting to third party service providers, and that is the reason that I am using the older versions. The Microsoft site does not tell me how to configure version 5.1 for STUN or for symmetric NAT. Every link that I have found for downloading version 4.6 points me back to the download page at microsoft.com, and microsoft has actually removed the file so all I get from them is a polite apology. Fair enough. So here is an interesting legal question that I suspect a lot of you SER wizards will know the answer to: Is it illegal for third parties sites to publicly offer the download of version 4.6 after microsoft has chosen to stop offering it? It was after all being given away free by Microsoft a short time ago. I am aware that freeworlddialup.com (FWD) is a good no-cost SIP service provider. Does FWD use SER as their server software? The latest version of FWD offers several options for User Agent software, but none of these UAs include a whiteboard feature, which I need for my tutoring service. Therefore, I need a SIP Service Provider which supports Windows Messenger 4.6/4.7 and has some configuration instructions for this particular UA. Hopefully the config instructions will tell me how to set Messenger up for STUN when I have a standard NAT, and for mediaproxy when I encounter a symmetric NAT. Googling for "SIP Service Provider" and "Windows Messenger 4.6" has led me to a lot of dead ends and out-of-date pages, such as the "old FWD site" at pulver.com which has detailed instructions for configuring Messenger 4.6, but the instructions no longer work. "Service provider temporarily unavailable". (permanently) Can anybody offer a Service Provider recommendation or volunteer to take me on as a customer? thanks Michael Kendall