ht-503 as a trunk

Hello
first thanks because I've already solved so many issues , just reading the forum. This time it's getting much harder for me with complicated settings of ht-503, which I'd like to use as outgoing (to fxo) and incoming trunk.
TRIXBOX TRUNK SETTING FOR HT503
Following some of the post I've found here I've configured a sip trunk for ht-503 in this way:
OUTGOING

username=503
type=peer&friend
secret=*****
port=5062
context=from-trunk
dtmfmode=rfc2833
canreinvite=no
host=192.168.1.85
nat=yes

at host I have the static address of ht503

left blank INCOMING AND REGISTRATION STRING

I've then done an outbound route using this trunk with this dial patterns:
00393z.
1z.
3z.
800.

ON THE HT-503
on basic settings I've done
Unconditional Call Forward to VOIP: 503@MYTRIXBOXIP : 5060

on FXO I've done mainly these settings
SIP Server: MYTRIXBOXIP
I've matched authentication
AC Termination Model = country based =Italy
Dial plan = {x+ }
Dial Plan Prefix: left empty
Wait for Dial-Tone: If set to no my pstn fxo carrier respond that the number I've dialed does not exist. If set to yes call goes out but not anymore in (from fxo to sip)
Stage Method = 1

on ht-503 statusI
i see fxo idle, not registered
sometimes after many reboot of trixbox and ht-503 i've managed to get some incoming calls from fxo, but usualy I get no answer from fxo
outgoing calls go out only if I leave Wait for Dial-Tone: yes

How I can configure this complicated box to pass all incoming fxo calls to trixbox and let sip users dial out the fxo ?

thanks so much