asterisk users - Oct 2006 - we are having trouble detecting the # for making a transfer from an E1, usually under some load, please help

Hi,  this is the setting:

a call comes in vi a first span  g0,    it get's hairpined to a second 
span g1,   fine,
on that second span we are accesing a legacy IVR,    at some stage  we 
need to get the call and transfer it  (hairpin) to another number via 
the same first span g0,  for that we dial a # and a number,  so the 
system tries to dial that number on the first span,
so in the end, the call  comes in via one slot of the g0  and goes out 
via another slot of the same g0, leaving unused the g1 for the IVR.

this works fine with one or two calls,  but when 4, 5 or 6 comes in then 
it seems as though * won't recognize the # tone we are dialing from the IVR.

does anyone have any idea,    we're quite urged here and will appreciate 
any kind of advise.

regards