We saw internal research from Nokia - see "NSN: VoLTE Beats OTT VoIP 4:0 !" - here and "Nokia: VoLTE is Doing Better than OTT's VoIP Under Load" - here.
Alcatel-Lucent joins the trend and announces "the results of an independent research study [Signals Research Group, here] which found that its commercially deployed Voice-over-LTE (VoLTE) technology provides better service than 3G Circuit Switched (CS) voice and Internet calling services and Skype software. The analysis found that VoLTE users enjoyed considerably better call quality, faster connectivity and substantially less drain on the batteries of their mobile devices"
- VoLTE call quality greatly exceeded that of 3G CS voice and was measurable higher than the HD voice service offered by Skype
- With network loading, and in particular with background applications running on the mobile phone and transferring data with the network, the VoLTE results were considerably better than Skype
- VoLTE call setup time was nearly twice as fast as 3G Circuit Switched Fallback (CSFB) call setup
- VoLTE used substantially fewer network resources than Skype voice, which in turn resulted in longer estimated device battery life for the subscriber and a more efficient network for the operator
- When leaving LTE coverage, VoLTE calls were successfully handed over to 3G CS voice. The network’s enhanced Single Radio Voice Call Continuity ensures calls continue without interruption
See "Signals Research Group study shows commercially deployed VoLTE service better than 3G and Internet calling services such as Skype™" - here.