NEC IP Phone one-way audio through VPN

Device: NEC DSX 40 Hybrid Key Telephone System.

Local: Digital phones on site
Remote: IP Phone

Network Setup: Site-to-Site VPN

Firewall1: Checkpoint (Local)
Firewall2: Juniper (Remote)

We are attempting to get an IP phone to communicate with the telephone switch via VPN. We've setup the VPN between sites and are able to connect the phone to the switch. We can see the lights for lines in use. We can make and receive phone calls, BUT voice traffic is only one way (from IP phone out). The IP Phone cannot receive any audio.

My rationale is that through the VPN everything is open as far as routed traffic, so I'm at a loss as to why voice traffic is only going one way.

I have tried opening up ports to the device, but I don't believe that should make a difference and I'm trying to get internal voice going both ways, before I worry about external.

Any help will be much appreciated.
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IAmDHConnect With a Mentor Author Commented:
Was finally able to get it working myself.

I'm not sure what fixed it though. Here's what I changed, though it seemed to not make a difference when I disabled them.

Policy Elements --> Services --> Custom
UDP & TCP - 3462-3463
UDP - 3455
UDP - 3458
UDP - 4000
UDP & TCP - 5060

Setup VIPs for all above to IP phone

Security --> ALG
Disable SIP
- enable NAT Mode
- enable Route Mode
Disable H323
- enable NAT Mode
- enable Route Mode
- enable Gate Source Port Any

IAmDHAuthor Commented:
Have yet to get any feedback... HELP!!
IAmDHAuthor Commented:
Feel free to confirm whether this works for you or not. These are the settings I changed in my Juniper firewall.
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