Direct SIP Dialing to TLD Issue

[mhemmes]

I'm having a strange thing happen when using SIP direct dial on one of my networks.

My Basic Setup:
• I have one company (Company 1) that is setup with a Pro license and a 3CX generated domain
• My other company (Company 2) also has a Pro license but is using their own FQDN
• Company 1 and Company 2 has Allow calls from/to external SIP URIs enabled and Company 2 is configured with the root domain as the local SIP domain (company2.com).
• All is working swimmingly on both companies, I have SRV records installed and can successfully make direct SIP calls using the root domain to Company 2 ([email protected]) while on using my iPhone 3CX client on cellular with no apparent problems - two-way audio works, etc.
• When I connect my iPhone to my Company 1 office wifi, I can no longer make calls to Company 2 using the root domain. It does in fact work using the 3CX host A record ([email protected]2.com).

Still troubleshooting this but wanted to through this out there because I couldn't find any questions like it.

 

[cobaltit]

Definitely weird but hard to determine what the problem is since you haven't clarified what your iPhone is connected to. Is your iPhone connected to the PBX at Company 1 in both cases, Company 2 in both cases, a completely separate 3CX system in both cases or?

 

[complex1]

@mhemmes

When you use the iPhone on local Office WiFi and it doesn't work, then try to use it using 3G and see if this will solve the issue?

 

[mhemmes]

Yes, this is what’s happening. I connect to Company 1 WiFi and I can only make SIP calls to Company 2 using the FQDN (the A record) of the 3CX server ([email protected]2.com). If I try to use the root domain, it never connects and times out. When I turn off WiFi and connect to cellular, I am able to use the root domain for SIP calls ([email protected]).

 

[JohnS_3CX]

Is the server is local to Company 1 and you are trying to reach your FQDN internally?

Perhaps it is because NAT loopback is prohibited in your network?

 

[mhemmes]

No, Company 1’s network is a different location. Remember that using the public A record of Company 2’s 3CX server works, which eliminates the worry of NAT traversal, etc.