That's weird, because September 2006, in my Firefox VoIP extensions, I wrote, "Also, while many Firefox VoIP extensions are SIP compliant, they can be tied to a specific VoIP service provider, thus you are stuck using their VoIP service plans. More proprietary games. Fortunately, with AbbeyPhone at least, you can enter your own SIP credentials to a 3rd-party VoIP service provider or even a SIP-based IP-PBX, such as Asterisk."
So was AbbeyPhone "open" back in 2006, then "closed" soon after, and then re-opened to any SIP provider today? I'm confused. I'll have to shoot an email to Luca.
Update: Not sure why I wrote AbbeyPhone worked with 3rd party SIP providers. Can't remember the source for that information. But Luca tells me that today is the 1st time AbbeyPhone supports any 3rd party SIP provider. This makes AbbeyPhone the first Firefox extension I am aware of that works with any SIP provider. I should mention that several VoIP providers are included in the extension: Free World Dialup, Gizmo Project, VoIPStunt, VoIPCheap and Abbeyphone.
Also this part of my 2006 article is interesting as a flashback to the history of VoIP extensions on Firefox:
Seems like everyone and his brother is developing VoIP extensions for Firefox. I wrote about Zoep which adds a VoIP extension to Firefox. It appears that Zoep's website is no longer available, so that project may have been killed. Openwengo is yet another VoIP player offering a VoIP extension to Firefox. Today, I was given a heads-up by Luca Filigheddu that AbbeyNetLabs, a VoIP service provider has just released VoIP extensions for Firefox and Thunderbird that runs on both Mac and Linux."