Thanks for the suggestions. I am continuously monitoring server load using htop and it is fine all the time never goes above 50%. Codec is Ulaw and there is no issue of bandwidth as we have fiber connection directly to ISP and download/upload is above 50 mbps.
1. Installation is done using vicibox 6.0.3 ISO so default installation no customization manually.
2. I have telephony servers (HP DL360 G5, 380 G5 and G6) having 4 core, 8 core and 16 cores processors. And according to the cores, Load is always below 50%. Like if 4 core then 1,5,10 minute average server load is below 2 and similar for other servers.
3. All servers are physical no virtualization.
4. Manual calling Dialplan
exten => _03.,1,AGI(agi-NVA_recording.agi,BOTH------Y---N---Y---N)
exten => _03.,n,Dial(sip/voipswitch/${EXTEN},,tTo)
exten => _03.,n,Hangup
Auto dialing dialplan
exten => _903XXXXXXXXX,1,AGI(
agi://127.0.0.1:4577/call_log)
exten => _903XXXXXXXXX,2,Dial(sip/voipswitch/${EXTEN:1},,tTor)
exten => _903XXXXXXXXX,3,Hangup
So just a prefix (9) which is removed in the second line.
5. I am more concerned with meet me conference, We tried by dialing meet me conference from agents phones, 4 agents in same conference room and it went fine for about 10 minutes. I am going to try Amfeltec PCIe x1 card on the upcoming monday, hopefully it will work fine, if it doesn't then I have no option except going for smaller telephony servers as recommended by Kumba in a topic.
Thanks a lot for helping us to understand this awesome solution.