You could try a clean chrome browser installation, with your proxy, and, I know for the UK, you can request free pay as you go sim cards, and they will turn up at your house, and you can pop them in and receive texts and calls, completely for free, no top up needed.
I've personally tried 3 brands, GiffGaff, Three and LycaMobile.
GiffGaff requires a top up to even tell you your number, however Three and Lyca, send you a text message when you put the sim card in, and it will tell you your phone number then.
Plus with Lyca, you can you can get a esim!