Question : VOIP

I have a mixed Windows / Linux environment. Windows is running my business systems while Linux is running as my firewall, web and e-mail servers.
What I need help with is the firewall aspect.
Overall it is running fine, however I do have one remote user who is running over OpenVPN with a business level cable connection a good amount of the time.
Over the OpenVPN he is running a softIP phone back to my phone system, however he is having issues with it.  One issue here is that the OpenVPN is running on TCP rather than UDP, I can change it to UDP and get a good connection however when I do this the softPhone will not connect back to the phone system.  On TCP it works fine, also if I log into his PC remotely I cannot seem to get any traffic to move back to my network when it is set to use UDP, no pinging, no tracert, nothing.  If I ping or tracert when on TCP it works.

So I need to get this fixed so that UDP works properly, it really is a better proto for VOIP traffic then TCP.

Alternatively and preferably..   I also have a sonic wall in house that I am not using.  Ultimately I would like to get it programmed up and used to replace the Linux firewall, perhaps this is the time to do it.  I havent had the time to do it and really I am much more a DB guy then a networking  guy.    At any rate the most important thing right now is to get my remote user up and running with a reasonable quality of service for his VOIP.

Answer : VOIP

In most cases to get around this people create a sip proxy.  You can google it and find plenty of linux applications that do this.  Then just limit the ip addresses to the users ip.  HTH but do not have enough information on your pbx/voip solution.