Lancom 1721 vpn + zywall 35 + asterisk

[hackfil]

Hi,

i user asterisk wms, but the telephone insides remote sips don't work.

I open the port on lancom 1721 vpn:

5004-5010
5060-5063
8000-8019
10000-15000

this pors "port forwarding" to the firewwall zywall35.

In zywall 35 , i have trained the "SIP ALG" and set port forwarding only the port 5060 to the asterisk.

The telephone rings but the voice doesn't feel him.

the inside telephones work in correct way, both in entrance and in exit


is there some other parameter that I owe settare in the lancom?

thanks
Filippo