I work for a German marketing institute as a telephone interviewer; working temporarily in Spain for two more months. For conducting interviews I've called polish companies in Poland from here in Spain with my Android 5.1 and a German SIM Card. However, after staying here for 4 months and talking many hours over the phone, my German provider told me I have to stop that or else they will charge me with Roaming fees which would cost me a fortune.
That is why I am looking for an alternative. My dad in Poland could send my a SIM card but I would be allowed calling Poland from abroad just for the first 4 months and afterwards I would have unlimited calls just in Poland which would also cost me much; at least 300€ because I would have to sign a contract which I mustn't terminate within the next two years. I think there is no tariff in the EU which would allow me for making unlimited international calls withing the EU.
Is there an application (via voIP like placetel or better) with a good call quality that would be cheaper for me that I could install on my smartphone to continue calling Poland?
Thanks for your time.