> Source: [sk102208](https://support.checkpoint.com/results/sk/sk102208)

# sk102208 - When remote access users connect to the local 600 / 1100 VPN server and establish VoIP Call, one of the sides is unable to hear anything

| Property | Value |
|----------|-------|
| Solution ID | sk102208 |
| Date Created | 2014-09-02 |
| Last Modified | 2020-11-09 |
| Technical Level | Advanced |
| Products | Spark Firewall (Locally Managed) |
| Versions | R82.00.X, R81.10.X |

## Symptoms

- * When a Remote access VPN user is establishing an outgoing VoIP Call on Check Point 600 / 1100 VPN server, one of the sides is unable to hear anything.   

* Debug output (`fw ctl zdebug + drop`) shows messages related to the Office Mode client IP:   

  "`dropped by fw_conn_inspect Reason: post lookup verification failed`".   

* Debug output (`#fw ctl zdebug + conn`) shows the reason for the above drop:   

  `FW-1: fw_log_bad_conn_ex: reason Connection contains real IP of NATed address`  
  `
  fw_conn_inspect: post lookup verification failed. Dropping packet`  
  `
  .....`  
  `
  VM Final action=VANISH`

## Cause

* Security Gateway cannot match backward connection on one of the created symbolic links in Connections Table, since connection was matched on more than one NAT rule.  

* The Security Gateway performs Hide NAT for internal connections even when it is not needed.

## Solution

This solution requires authentication. Please log in to view the full solution.

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