I like how it works with matrix sim cards --- my sister was going to Germany for almost 45 days and we wanted to be in touch with her all the time. So we got her a german sim card from matrix sims about 10 days back. We loved the fact that she could carry a post paid number without any hassles we got the bundled plans which had a combined service like calls to India, data and even local calls which was very cost effective . Her number was active the moment she landed. Data works just fine cs she keeps on sending us pictures. Although I haven’t used matrix sims but with this indirect experience and my sister being comfortable so far, I can definitely say that they will be worth a try for any traveller.