How should I interpret this CAN bus protocol - J1939
This is what happens when incompetent non-programmers are allowed to document raw binary data...
All programmers in the world, as well as the CAN standard, as well as the J1939 standard, all enumerate both bits and bytes starting with 0. But the incompetent person who wrote this document did not. They even managed floating point notation here and there.
Now how do we know that they name MSB bit 7 (or 8) rather than 1? Since we already established that they aren't using standard or engineering praxis, we don't...
As far as I remember, J1939 also requires little endian for word-sized chunks, but whether or not that applies here, we can't know either, since the document just writes 0xFE00 etc and we can't know if this is the raw byte dump from the bus or the numeric value after little endian has been applied.
So this so-called documentation will ultimately have to be accompanied with trial &amp; error and a live bus listener.
We can only guess that they meant to say something like this:

Given the first byte of the payload, called byte 0 by the CAN standard and by engineers (1 in the document) lets say you have something like for example 0x02.
The 2 in that byte is called bit 0-3 to by engineers (maybe 1-4 in the document? we can't know). A guess is that this would represent TelecomConnectionStatus = Connected.
Then the MS nibble 0 called bit 4-7 by engineers (bit 5 in the document, maybe?) and represents TelecomNetworkTechnologyInUse = gsm.

You have to verify that this is so by connecting to a live bus. Then hopefully the document is consistent across multiple packages.