Cell phone frequency range?

[TheawesomeMCB]

So I’m currently looking for a cell extender however I’m trying to figure out what would be best. So I can’t find the range of what each frequency is. So my phone is AT&T GSM and the place I need to get signal has 3 bands to work with. 700mhz (band 12), 850mhz (band 5) and 1900mhz (band 2). I think that 700mhz has the most range but I don’t know about speed. But I’m trying to limit my budget to one of them instead of 2. Should I get the 700mhz or the 850mhz/1900mhz (2 in 1). I have the outdoor antenna already and the cable, I just need to find a indoor one which should be cheap. I just need to know what would be the best one to get between the 2. The 700mhz or the 850mhz/1900hz combo and what is the range of each frequency and which ones can penetrate the most blockage (example: a rock or mountain)