atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems SV8100 Remote IP phones

You say "this ministry has their routing and there are routers for PALTEL in the way to make the HQ and branch speech together , the HQ and branch speech together from LAN IP router like 10.111.73.X can talk with 10.110.74.X without need to WAN port in the router the WAN port to make Ministry router talk with PALTEL Router which are in the WAY this interface has IP 172.23.21.X"

I don't think everyone is quit following the description of this customers network. But it sounds like it's an "MPLS" type setup where the carrier provides a router for the customer. The customer has routers as well that are being used behind the carriers routers.

Hopefully, the carriers routers pass all packets through to let the customer route the packets. If not, it'll be tough because the issue could be on either the carriers router or the customers router.
Static routes should be built in the customers router to allow the necessary range of ports through to the phone system.

Bottom line is this - if you can ping the VoIP IP while on the same LAN as the phone system, but cannot ping when outside of that LAN, there are ports blocked.

I don't think they will believe that.
He keeps saying no ports blocked but have they looked?

Wireshark it.

what is the best test i should do to make customer convince there is problem in their network ?

I agree with 'brokeda'. Run Wireshark Traces. Have them mirror the port the PBX is plugged in to with a port your laptop is plugged into. Then use the "ip.addr==xxx.xxx.xxx.xxx" filter to look for the IP Address of the remote phone.