Asterisk hangs after two weeks

Hello Friends,

We are using elastix based call center setup. We are getting incoming calls nearly 3000 on daily basis. At peak hours we can expect more 40 or near concurrent calls.

The voices are breaking after two or three weeks. Things are getting normal after restart asterisk or system.

I noticed that when using top -c command, the virtual memory goes beyond the 4 MB, asterisk became crazy.

System Details,

OS : CENT OS 5 64 bit
Asterisk = 11.12.0

I just google and found some of the memory releasing guides without restarting the server.

Will above guidance works for me ?

your guidance are most welcome.