There is no known way to easily record a Google Hangouts call (see this question).
Are there any reliable VoIP clients that allow making free outgoing phone calls that either include recording capability, or that are compatible with other recording apps?
Note that supporting incoming calls is not required, but the ability to make outgoing calls through the POTS (Plain Old Telephone System) network is required (cannot only support VoIP-to-VoIP).
Prefer gratis, but a one-time payment for the app is acceptable. No per-minute or monthly fees, please.
Support for either Android or Windows is needed. Does not need to support both.