I have been experimenting with OpenWengo 2.1.2 (from Hardy repository), Ekiga, Twinkle, Gizmo5, Jabbin and Empathy. On my Nokia 6121 Classic I have tried Fring, Talkonaut, Gizmo5, Nimbuzz and Symmy.
Right now, I have settled down on running both Meebo.com, OpenWengo and Skype side-by-side with each other, with Fring and Gizmo5 on my mobile phone.
- Meebo.com - for all my IM. I prefer my chat logs to be stored in the clouds.
- OpenWengo - Works well with VoipDiscount. Just log out and create a new Profile to log in with the VoipDiscount info.
- Skype - For IM with Skype users, what else. If only Meebo.com or OpenWengo support Skype and voice or vice versa... : (
- Fring - Closed source but the best all-in-one. It connects to all my IM, including Skype AND can make both SkypeOut and SIP calls. 2 caveats though: Fring does not have SMS and you can only see the nicknames not email addresses of your IM buddies.
- Gizmo5 - I leave this on my phone purely for SMS purposes.
Jabbin and Empathy are both not mature enough yet, imho. The interface, ease of installation, ease of setting up, number of users adopting them etc. all beg for more time.
Twinkle is a KDE program but I prefer non-KDE programs if available, because KDE software usually shows every single option available in any configuration dialog instead of offering Basic and Advanced views. That is, too time-consuming trying to read or figure out what each option means!! *ready for KDE flames*
Gizmo5? Proprietary software that is almost perfect, but does NOT allow you to use their competitors' SIP services. (eg. VoipDiscount) It does pretend to connect for a while, though. p/s. Gizmo5 SMS on Symbian S60 phones is good! Fring, Talkonaut and possibly Nimbuzz do NOT have SMS.
Ekiga? The WORST of the lot. Cannot register to VoipDiscount service, and worse, cannot register to its own Ekiga.net service even!
On the phone, Talknonaut, Nimbuzz and Symmy are out. Talkonaut only works well with SipPhone or their own service providers and refuses to work consistently with VoipDiscount. Nimbuzz seems to use PSTN for some stuff (cannot recall offhand) so it defeats my vision of communicating on 3G Internet-Only. (To be fair to Symmy, I did not get to use it yet, since I was too lazy to create yet another VoIP account)
Having said everything, I hope that Fring can become Open Source AND continue to innovate, lead and improve. (eg. allowing users to see their buddies' email addresses)
Last but not least, I hope that OpenWengo gets into version 2.2 soon, as I read that the future of the project is currently uncertain due to it no longer having any corporate leadership. If you are a developer who loves open source VoIP, I implore you to help OpenWengo!
Hope that helps.