One way sound

Hi!

my asterisk server is behind nat, and i may use the voip service mikrohalo. there is voice only from my inner sip phones, so this may be a port forwarding problem. recently i set up a far softphone(xlite), that has a fix ip. from that i have 2-way voice, across mikrohalo, or when calling an inner ipphone.

could it be a firewall setup problem?
or something else? or bad configuration of the phones itself?

here is my firewall setting:

Chain FORWARD (policy DROP)
target prot opt source destination
ACCEPT all – 192.168.1.0/24 anywhere
ACCEPT all – anywhere 192.168.1.0/24
ACCEPT udp – anywhere ast.server udp dpt:5060
ACCEPT udp – anywhere ast.server udp dpts:10000:30000

Chain PREROUTING (policy ACCEPT)
target prot opt source destination
DNAT tcp – 192.168.1.0/24 anywhere tcp dpt:ftp to:192.168.1.1:2121
DNAT tcp – anywhere anywhere tcp dpt:5000 to:192.168.1.22:22
DNAT udp – anywhere 192.168.1.0/24 udp dpt:5060 to:192.168.1.20
DNAT udp – anywhere 192.168.1.0/24 udp dpts:1000:30000 to:ast.server
DNAT udp – anywhere server dpt:5060 to:192.168.1.20:5060
DNAT udp – anywhere server dpts:10000:30000 to:192.168.1.2-192.168.1.254

Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
MASQUERADE all – 192.168.1.0/24 anywhere