This would work great on the Nook B&W, too.
cheaper than TPO and even Ting
no international service, but you could switch SIMs
seems like these require a writeable NFC tag
Can't tell if Proxoid works on Linux clients.
some explanation for all the dropped/rejected calls on iPhones
Tizen (/ˈtaɪzɛn/) is an operating system for devices including smartphones, tablets, in-vehicle infotainment (IVI) devices, and smart TVs.
Free version transcribes the first 10 voicemails a month. Still requires conditional forwarding setup like YouMail, but reviews pretty well.
Talkatone http://www.talkatone.com
TextNow http://www.textnow.com - also offers mobile service, similar to Republic Wireless
GrooveIP https://snrblabs.com/GrooVeIp - Android only, limited use for free
Visual voicemail and robocall blocking
YouMail https://www.youmail.com
My Visual Voicemail https://play.google.com/store/apps/details?id=com.vna.service.vvm
CallControl/EveryCall https://www.callcontrol.com/
Truecaller https://www.truecaller.com/
Should I Answer? https://www.shouldianswer.net/
Nomorobo http://nomorobo.com/ free for (some) voip lines
Hiya https://www.hiya.com/products/app recommended by AT&T, freemium