JMP.chat is a commercial provider, but their infrastructure is open-source. The central bridging component is actually cheogram.com (maintained by the same team). If you're determined enough, there are other providers you can bridge through Cheogram, including Vonage and Twilio, which offer European numbers. It's not as seamless as JMP, but if you're determined enough it works: https://wiki.soprani.ca/VonageSetup and https://wiki.soprani.ca/TwilioSetup

Alternatively, hang tight... I know JMP do want to offer European numbers at some point.