Input:
Remote Office #3 via RB4011iGS 6.47.8
1. Incoming WAN connection static address
2. vpn connection via pptp to the office No. 1
3. vpn connection via pptp to the office No. 2
4. sip server on the local network in office #1
Remote office # 3 sees and walks through the resources of office #1 and office #2, all local resources, databases, and so on are available.
But sip phones of remote office #3 do not want to see the sip server in office #1. Pings pass, registration via tcp passes, there is no voice, registration via udp does not go.
there are No firewall settings. The NAT settings are visible in the screenshot.
Why don't udp packets go and what rule to make?

Hi,
go to IP-FIREWALL-SERVICE PORT - SIP
Disable SIP service and reboot your router
try again it should work :)