Call recording from handset

[sunstate]

I have seen people in the past mention that they are initiating call recording from the handsets, in particular with Yealinks. When this is set up, are they just turning call recording on/off for that extension (as in this setup http://www.3cx.com/blog/voip-howto/call-recording-with-aastra-5i-ip-phone/), or are they actually initiating an ad-hoc recording of that particular call the same way you would do via MyPhone? If so, is there any howto's on programming the buttons?