asterisk users - Jun 2005 - Missing first second of voice on outgoing SIP/IAX calls

I've been curious about why this happens for the longest time.  When I
make an outgoing SIP/IAX call the first half second or so of the voice
never makes it to me.  This is consistant on every provider I have
used except for voicepulse, and it always happens.  With voicepulse it
never happens.  It doesn't seem to make any difference whether it's
SIP or IAX.  I don't really want to mention any names because this
isn't really a gripe, it's just got me very curious.

On these same providers I do not get the lost voice on incoming calls.

Anyone have any ideas?   The only thing I can think of is that maybe
voicepulse isn't using asterisk?

Chris