As far as I understand Ubuntu Touch is basically open source. But is it completely open source? Are all the drivers open source? Are there any binary blobs?  

I guess my actual question is: Can I use Ubuntu Touch without running anything that is closed source? 

If I recall correctly, on Android (even though Android per se is open source) you couldn't really use it as a phone unless you install some closed source qualcomm services (or something along the lines of that). So I always assumed that the drivers for the baseband related components would be closed source. 

But then I read that Ubuntu Touch can only support devices that have an open source device tree. I'm still not entirely sure what that means in terms of being able to write drivers for the device, though.  

Does this mean that we actually don't need to use any closed source drivers to get gsm, 3g etc working?

My device for instance (OnePlus One) has an open source device tree, [which can be found here](https://github.com/CyanogenMod/android_device_oneplus_bacon). But if you look closely you find things like that: [WCNSS\_qcom\_wlan\_nv.bin](https://github.com/CyanogenMod/android_device_oneplus_bacon/blob/cm-14.1/wifi/WCNSS_qcom_wlan_nv.bin) which make me wonder how open source it actually is.