I think very hard to make I found this comment;
Here is what you need, if..
a) If you have a 1st Gen Touch, and you are running OS1.x.x,
Mic: you will need a Mic based on the DIY tutorial from our Wiki.
VoIP SW: you just need to add one of our Touchmods repositories to installer:
http://www.touchmods.org/repo.xml
http://touchmods.net/rep.xml
and install Siphon or SIP-VoIP.
more info in the Wiki or Blog @
http://www.touchmods.org.
b) If you have a 1st Gen Touch, and you are running OS2.1
Mic: AFWK, no Mic is compatible with this technology
VoIP: still you can at least listen to the other party if you proceed acc, to point c)
c) If you have a 1st Gen Touch, and you are running OS2.2,
Mic: you will need a Mic with a HW key inside. A HW key that is approved by apple. Such a mics are: iVoice III from Macally
VoIP: You will need the latest Siphon form Cydia. Cydia is installed automatically when jailbraking your Touch.
d) If you have a 2st Gen Touch, and you are running OS2.x,
Mic: you will need the white apple headset made for the latest iPod devices
VoIP: jailbreaking exist since Jan.2009, so beside the appStore apps, there is Siphon waiting for you on Cydia.
To get to know more about Siphon, SIP-VoIP, the DIY mics, Audio Input compatibility of different OS versions, pls refer to our Wiki, and to other links on the right side of our touchmods.wordpress.com blog.