1src has a page where you can buy microphones for your Tungsten T5 / TX. You put them into the multiconnector:

I’m manufacturing External Microphones for the Palm T5 and the TX. Simply attach to the bottom of the unit and you now have recording capability. $20 US plus $6 shipping (US) $12 shipping (International). I use Priority Mail (usually 2-3 business days) and Global Priority for international shipments.This also enables your Palm to use Mobi VoIP for making voice calls to telephones around the world!

Email me at: markspdaplus [a t] yahoo.com for info.

WyreNut

Product Page

With a microphone, you can use your T5/TX as a voice recorder, or as a telephone with an IP phone software.