* App recording VOIP calls  is possible, see [Call Recorder - IntCall](https://play.google.com/store/apps/details?id=com.GG.CallRecorder) for instance. There may be others too

* Non app based services that record VOIP calls seem to be more - [Dingtone](http://www.dingtone.me/), for example

What is *common* for VOIP recording and *different* from voice recording is that VOIP recording is done when it is routed through **the servers provided by the app** (see description in both links above). Ordinary voice recording is not bound by such limitations and can be natively record if enabled on device (I haven't found any reason *why* routing through third party servers is required and will update of I find)

Perhaps, routing the call through third party servers has legal and security implications besides being a technical limitation to natively record on the cell phone