[Asterisk-Users] how many oh323

[Altus Snyman]

Good day.
I  configured asterisk and oh323.Im using it as a sip-h323 convertor
A call will come in to the asterisk box via IAX and be send to a quintum 
h323 gateway.
in oh323 you can set the max in,out and simultaneous calls, Ive set them 
all to 100.
Calls coming in via iax is alaw and then goes out h323 g729.
It is a P4 3.3 and 1Gig of ram.Yet at 20+ calls, calls start failing.
Is there someone else with a setup like this.Is the problem on the 
asterisk side or the quintum
Please help
Thanks
Altus