Asterisk behind PFSense 2.0.3 works partially

We have 1 PFSense firewall with 3 ports- WAN, LAN and OPT. Following are some additional details:
• The WAN is connected to a Comcast business router with 4 physical ports. We have a 16 public IPs and one of these is assigned to the WAN port.
• The LAN port is connected to a switch and we have 4 VLANs. The LAN hosts some servers that have public IPs (via NAT, port forwarding).
• The OPT is dedicated for Asterisk and is connected directly to it. The Asterisk box has a public IP assigned to it.
• VOIP clients are on the LAN (x-lite, snom phones) and also some are on the outside (of WAN).
• We use Manual Outbound Rules.
We have tried the following two configurations with problems we are facing:

  1. Bridged mode between OPT and WAN. In this mode,
  2. In 1:1 NAT mode using VIPs.
    In both configurations SIP clients (all softphones) outside WAN can connect and use the Asterisk server w/o issues. But the problem occurs for SIP clients who are inside the LAN (connecting using the local IP of the Asterisk box, cannot connect using public IP). These clients are facing these problems:
  3. In 1:1 NAT mode –
    a. Outgoing calls – audio comes in but does not go out. Audio drops at 20 secs and then call disconnects at 30 secs.
    b. Inbound calls – there is no audio transfer either way and the call disconnects in 30 secs.
  4. In bridged mode
    a. Outgoing calls – no audio transfer either way.
    b. Inbound call - audio comes in but does not go out.
    Any help is appreciated.