Very possible. I wonder if NSA has the call recorded. It'd be really interesting to hear exactly what was said. And not just Jeantel's version of it.
In any event, the jury was able to conclude the evidence pointed to self defense even without knowing:
What you bring up here is very interesting. The powers that be may very well have information about what happened that night that we haven't heard yet. Didn't the FBI look into this? Given how zealous the administration seems to be to find a way to nail Zimmerman, it makes me think that whatever information is out there does not support the leftist agenda.