Memery problems

hi,all

   I test Asterisk by SIPp.My Asterisk box is P4 2.8 1G@radhat 9.0

I found some memery problems and channels problems below:

  Test : no rtp maintain

35cps call to asterisk
and 4464 sucessful 133 failed
I type sip show channels on Console,found 8 channles by"ACK" die

120cap call to Asterisk
8channles by “ACK” die

127caps call to Asterisk
8channles by “ACK” die

keep 5s RTP maintain
120caps call
28 channles by “ACK” die

35caps call
18 channles by “ACK” die

after these test I found my box free memery down to 718944k (start is 958040k after Asterisk running) with TOP in linux

So my result is
Asterisk can 30caps and max 127 calls in the same time