Hi,
The question is not "could". Any BTS always needs a proper, stable
reference
clock. So unless your BTS has a built-in GPS clock refrence (and that reference is configured/enabled), your E1 will have to provide a stable
clock
reference.
How does the BTS judge if the clock satisfies its needs? Less sophisticated systems don't care and simply are unstable / off the frequency when the master clock is unstable / off-freq. The question is just because I am technically interested in the topic. Everyday there pops up some exciting stuff to learn out there :)
Ralph.