@ Kathy, yes it is clear different ISPs in different countries use different methods. According to Wikipedia voicemail:

However many people do have to pay for using voicemail (PAYG or having free minutes in subscription or not). Having the stuff local allows for much more versatile configuration, and allows even to centralize VoIP (e.g. Skype)/SIP voicemail to be combined with GSM voicemail.

When I had an answering machine on my home line I never had to dial some special number to hear my voicemails. They were recorded local. It really makes little sense to save them remotely, and _if_ saved remotely it makes sense to fetch them from the server and then decide what to do with them. Imagine your mail server asking you if you really want to download the spam or delete it then telling you how many messages remaining meanwhile you're paying for the seconds to listen to this artificial nonsense wasting your time; that is voicemail on GSM. Although perhaps deserves a seperate topic (Brainstorm) to fix the issue has been discussed before on t.m.o.

Thanks for your post, I think you're on the right way for getting the UI right.

However IMO one engine should be used (Tracker) with a backend for the protocols (SMS, VoIP, GSM, ...). With flags a shortcut can be made. Like for example: tracker --search backend=gsm filter=none. From there, one can modify the filter or use more backends. My point is: why use different search program or different UI when using different protocol (VoIP or IM different than GSM or SMS)?

Instead, make it unified, like the profiles don't care about protocol you use to communicate with either; they store them all. Then the 'gsm communication log' should use the frameworks as the 'general communication log'. If yes, why not simply use the same interface with default options which make sense from the protocol used (e.g. log called from GSM goes by default for GSM but allows more)?

One problem is 'Missing' has different context in IM/SMS/e-mail than in VoIP/SIP/GSM, and I'm not sure how to solve this because there is no authentication in IM/SMS the other side has read the message.