Unity 5, exchange 2007 long pauses in greeting

[Burgal]

I upgraded to unity 5 a little while back. Ever since then when you call into a users voicemail you quite often get a LONG pause of like 10 - 15 seconds before the greeting starts playing. Just dead air.

It was doing this with both exchange 2003 and 2007.
Running unity 5 on an HP DL320-G3, PIV 3.4ghz, 2gb ram, SATA RAID 1 and windows 2003.

Unity 4.2 didn't do that.