how to scan GSM1800 and GSM2100 with kalibrate?

[saintofinternet]

currently i am able to scan the 900Mhz band with Kalibrate but how can the scope be increased to GSM1800 or GSM2100 ??

[krak3n77]

currently i am able to scan the 900Mhz band with Kalibrate but how can the scope be increased to GSM1800 or GSM2100 ??
I'm not a dev, but i can see this project uses the rtl sdr, which most of the time cannot pick up 2100 Mhz, which is the frequency of GSM2100, Using a adapter, such as in this project on the rtl sdr blogs site: https://www.rtl-sdr.com/receive-up-to-4-5-ghz-on-your-rtl-sdr-for-5-using-a-directv-downconverter/ would possibly allow you to use such frequencies, I cannot vouch for that, as I have never used a downconverter. Seeing as the rtl sdr does not natively support 1.7 GHZ, i would assume thats why the developer left it out.