EDIT: They are not accepting new accounts at this time. Sorry, maybe later. Just learned about this "free" calling app that I was unaware of from a poster on DSL Reports. Works on Google Browser on PCs and can be used on most Android phones. FireRTC is linked below. This would work great in conjunction with a Truphone sim--- free incoming and outgoing calls. Anyway, worth a look. Evidently, one can make free calls to the UK now, too.
QBZappy wrote: " I have an account with an online free phone service "FireRTC". When they first came out they offered a free USA DID with the ability to receive calls. They have since changed their model to outgoing calls only. No more DID numbers offered. You can configure the CID so that returning calls go directly to your cell. They promote their service as "FireRTC is a free online phone". I only knew of FireRTC and Google Hangouts which could make calls using the browser. TextNow and perhaps some of these other services offer browser based calling as well. Possible use case is to setup one of these online services for overseas relatives to call our cell phones directly."