Well, finally we have found a way to get the accounts for a contact on maemo. We need this to be able to identify the contact which the user has called through "Internet Call".
As you may have read in the post about "watching for calls through telepathy", you can have noted that all the contact information available was just an URI, kind of "sip:email@example.com". However, this info is only enough to supply a way to search for contacts which has this URI as account "specification".
So the question over this week was: How maemo store the accounts available for a contact?. Basically, how do you can get the list of accounts by which you can make a conversation with the contact?
We've looked at the APIs available (ebook, abook, mission-control, ...) and nothing seemed to supply the list... so I went to the database file and the first attempt was to try open it and investigate tables structure or something similar that could give me some information. No way there, the db is a Berkeley DB and there is no python modules to manage this kind of database (python for maemo seems to have removed this standard module of the distribution) and I wasn't disposed to try it in C (to work with a "mysterious" DB in C was not the kind of fun that I would like to play at the moment, at least with python this could be a bit easier).
Then I had the idea to try get the VCARD info for a contact and... WELL, the information was there. One thing that I forgot to say is that through the APIs I could get each information (named "fields" there) for the contact (first name, last name, email and so forth), but the accounts wasn't available through "fields", since you can have an variable number of accounts and the function to get a contact field expects a well defined constant (note, the "vcard" is a "well defined constant").
Through the vcard, you get things like:
The "X-SIP" value is the user account which the contact account is mapped to. For example: I've two accounts on the device: gtalk and SIP. I've the contact X which I can talk through gtalk, the contact Y I can talk through gtalk and SIP... so you need a way to say what is the user account the contact account is bounded to (in the example, for the contact Y you could ask if his account is a "gtalk" or "sip" account), it servers as an "account type" identifier.
Given this, you can now map your "sip uri" available through the "calls watcher" to a real contact on the system. If you can do this, you can get all the other contact info, like the general ones available on most of the softwares (like name, email, web address, phone and another ways to contact the same person :)
Hope this information can help some people having to do this kind of interaction with maemo's rtcomm.