For running simple tasks, i.e. hosting an Asterisk PBX system, my preference is a Linux embedded system. The reasons are simple, no noise, and operational cost is at a minimal.
I have a FON2100 WiFi router that has been flashed with an OpenWRT firmware and turned into a Linux embedded system to host my Asterisk PBX system. Its AC/DC adapter is rated 5VDC @2Amps (10Watts). It has a limited 8/16MB Flash/RAM capacity. So, logging activities have been disabled.
Also, I have another Asterisk PBX system hosted on a long discontinue Netgear WGT634U WiFi router flashed with an OpenWRT firmware. Its AC/DC adapter is rated 12VDC @1Amp (12Watts). It has no problem to log I/O calls on a USB memory stick plugged into its USB port. It even can e-mail out voicemails. If I had an SMS capable phone, I am sure it can also do SMS. So, depending on what you want to achieve, a simple hardware, like a long discontinue Netgear WGT634U WiFi router, can do a lot for a much less operational cost in electricity than a full-blown computer (200+ Watts?) to waste a lot of electricity.