thank you Daniel 3- the key is created as follows: a.b.c.d:5060:X.Y.Z where "a.b.c.d" is the IP where we receive the call on, IP of the proxy "X.Y.Z" are the first 3 octets of the source IP, customer sending calls to the proxy
some times they are very similar for example 10.20.30.41:5060:10.20.30
for 4 I will look into your suggestion
by the way the kamailio has 16 GB of ram, this is the output of "kamcmd core.shmmem"
`[root@aw-atl-proxy-02 sbin]# ./kamcmd core.shmmem { total: -2147483648 free: 2108379744 used: 37308232 real_used: 39103904 max_used: 39571432 fragments: 6458 } `