This is a veery interesting project and I'm following it closely. I unfortunately have no ideas right now. My usual strategy is to examine the source for similiar apps, but there is no app which uses IVRS (interactive voice response) function or plays audio to caller. Lemme try to dig something else up...

Of course recording calls can be done by activating recaller at the same time, setting it to autorecord all calls, this should work just fine since in this mode the N900 automatic takes the call, so here it would record everything caller is saying and hopefully not recording the message being played the other way.

im going to mess around with alsamixer and see if i can UNMUTE what the Phonesystem is muting when getting a call.

Just as a pointer:
maybe package
fm-carkit
can give you some hints. It routes the (incoming) sound to fm transmitter.

the only app I have seen so far that has played audio back into a call(although inadvertently) was qradio. code changes in Version 0.4.1 disabled calling arty hearing radio audio, so maybe you can exploit wahtever was happening prior to that to play audio back into call. pehaps with some direct control of the fm/bt chip you can get low enough to pipe audio in there.

then your next problem is decoding dtmf from incoming audio stream

thanks for all of your work. good luck!

While I like this idea, I think it's a touch redundant. There are at least 4 ways to skin this cat, and this looks like the hardest one. That said, it looks like you're 90% done with it already, so... Yay for existing community tools! And really, who doesn't want another way to skin a cat?

The most trivial way is to go into off-line mode. Your carrier will forward all things to your voicemail.

Another way would be to use existing tools (cron or QBW, and forwarder) to make it so at set times or when activated it just forwards all calls directly to your existing voicemail. You should get a log that someone called, but the phone would not ring.

Alternatively, you could use an on-line service to do this for you, like Google Voice. Give out your voice number, and have it forward to your cell. Voice can be set to give custom messages during set times. There are also extensions and apps to allow for dial-through and do direct SMSing through GV to preserve that origin number for outbound traffic.

While I love the concept of what you're doing, it feels like killing a fly with a shotgun. Fun if you like shotguns, I suppose... but probably not the most efficient way.

As for what you're actually doing: I think the hard part will be manipulating the mic/input side of things while the default Nokia phone app is running so people don't hear a second of whatever's going on on your side. A second may not seem like much, but just image if that ring picked up just in time to hear: "<ring> OH! Yes! Bab... <click> I can't come to phone right now. Please leave...."

other than that, it might be easier to run asterisk locally on the phone, forward gsm calls over a service provider sip trunk to local asterisk and deal with them there.

Im not trying to forward calls or let them go to a normal voicemail.

I'm trying to make a "do not disturb unless really important" system, one where if you have to catch up on sleep or in a meeting and only want to be disturbed when important..

also one more thing i just thought of, not having to call voice mail to hear messages

i totally like this idea! would definitely use it if such a tool makes it's way to our n900
...and yeah maybe it's like using a shotgun to kill a fly - but to me forwarding the call and then handle it elsewhere looks like using a shotgun for that with the need of shooting twice :P

the "problem" with just rerouting the call (no matter how) is that the caller hasn't the chance to let you know this call is very important and he want's to talk to you no matter what you are doing at the moment...

Im guessing you are think about those people that just has to tell you about the new hair product they just discovered and that's MEGA important news you just have to know even if you are bald (guilty ).

Well here is an add on for that, when my system that i made so far is running it takes down the number, hence a BLACKLIST .

For the record i don't have anybody that just calls me with cr*p like that

not having to call will also avoid costs if carrier charges for voicemail service (not sure many do still). it would also avoid phone/voicemail hacking by avoiding standard services.