Unity 4.2(1) TSP 8.1.3 with failover

CM 4.1(3)sr4d

Unified Messaging w/ Exchange 2003

I'm having some odd series of error messages popping up. For the most part they are Miu 550 or 549 and TSP 158 errors. I'm getting them in clusters for a fairly large number of ports. I've dug into it a bit, and at least a few of the times it has happened, it has happened right after a failover event (ie, lose connection to secondary, ports start unregistering, but then just seconds later contact is re-established and ports re-register).

My question is, can someone give me an idea of why you might get Miu 550 or 549 or TSP 158 errors? I've put them into the tool on ciscounitysupport.com, but the causes listed only seem to reference very out of date TSP versions. We don't have end users complaining of symptoms yet, we're just concerned at the large numbers of Error events showing up.

Thanks,

Jim