Hi I am tring to benchmark freeswitch call capacity. But After 700 concurrent call load i am getting some distortion and other problems (Mentioned below). I need your help to tune my freeswitch server or freeswitch with which i can reach at higher concurrent calls. My Setup: I have 2 servers. *Sipp Server:* OS : Centos 6.2 64 bit. RAM . 2 GB *FreeSwitch Server:* OS : RHEL 6.2 64 bit. RAM . 4 GB freeswitch Version 1.5.15b *a-* when i was trying for 500 concurrent call to freeswitch using following command ./sipp -i 10.168.1.10 -sf data/uac_raj.xml 10.168.1.25:6060 -s 12345 -r 50 -l 500 -m 3000 -t u1 -inf data/number3.lst -trace_err -max_socket 503 its was working fine in following terms 1-After 500 concurrent calls load i make a call from softphone. Voice quality was good. 2- quick response from freeswitch 3-call duration was fixed for each call. (In CDR i found call duration 24 for all calls) 4-all 3000 call are successfully completed *b-* when i was trying for 700 to 1200 concurrent call to freeswitch using following command *For 700 calls* ./sipp -i 10.168.1.10 -sf data/uac_raj.xml 10.168.1.25:6060 -s 12345 -r 70 -l 700 -m 3000 -t u1 -inf data/number3.lst -trace_err -max_socket 703 *For 1200 calls* ./sipp -i 10.168.1.10 -sf data/uac_raj.xml 10.168.1.25:6060 -s 12345 -r 120 -l 1200 -m 3000 -t u1 -inf data/number3.lst -trace_err -max_socket 1203 *its was working fine in following terms* 1-quick response from freeswitch 2-all 3000 call are successfully completed *its was not working fine in following terms* 1- I was getting some distortion in voice , in my test call from soft phone 2- In CDR file , call duration for all calls was varying. *c-* when i was trying for more than 1200 concurrent call to freeswitch using following command ./sipp -i 10.168.1.10 -sf data/uac_raj.xml 10.168.1.25:6060 -s 12345 -r 130 -l 1300 -m 3000 -t u1 -inf data/number3.lst -trace_err -max_socket 1303 *its was not working fine in following terms* 1- I was getting some distortion in voice , in my test call from soft phone 2- In CDR file , call duration for all calls was varying. 3- At softphone call i was getting ANSWER response very late. -- *Jeevan Singh Dhami* *(9650541245)*