Unrestricted APN for VOIP

[Intell1gence]

Hi,

We have had problems with our VOIP line not connecting (Trying, timeout etc) properly and thus unable to make or receive calls for the last couple of weeks. Everything was working for months/years before now. First i thought it was due to loadshedding but it cant be.

So i reached out to the provider and they asked me if i was on Vodacom LTE, so i asked them if they are experiencing any issues with Vodacom LTE? They told me that Vodacom have receintly changed the way they handle VOIP services and the like and this was causing some users with the problem we are seeing.

They told me to ask Vodacom for their Unrestricted APN settings.

Now this is bothering me. How can this be safe to unrestrict all incoming traffic this way? Is this is the correct way to handle this situation?

Thanks for your input

 

[Guest 290922]

Totally agree with this. Vodacom should only open the ports you need for the VoIP. Removing the entire firewall for a single port is just not cool.

 

[Vince0]

Try SIP over TCP instead of UDP, LTE providers will often block UDP only. Or a VPN if your VOIP provider services it. LTE routers are also often a problem - disable SIP ALG if it has an option.

 

[deweyzeph]

You do not need to port forward any ports for VOIP to work if you are connecting to an external VOIP server. This is a common misconception. I've been using VOIP at home for years and I do not forward any ports to my VOIP devices or use SIP ALG.

 

[Vince0]

Correct Dewey, never open inbound ports to a voip system it will get brute forced all day.

 

[deweyzeph]

Correct Dewey, never open inbound ports to a voip system it will get brute forced all day.

Yip, and it irritates me no end when any VOIP provider recommends doing this as a default troubleshooting tip for when things don't work. Massive security risk to have your SIP phone's port open to the world on your external IP address. Plus you'll get endless "ghost calls" in the middle of the night.

 

[Intell1gence]

Try SIP over TCP instead of UDP, LTE providers will often block UDP only. Or a VPN if your VOIP provider services it. LTE routers are also often a problem - disable SIP ALG if it has an option.

Thank you @Vince0, i really appreciate your reply.
SIP ALG was disabled but ive changed the transport protocol over to TCP. I also have a TLS option on my Fanvil (which seem better due to the encryption), but im getting a timeout error if i select it.

Is there anything else i can do/change to improve quality/reliability/minimize firewall or ISP issues? Im currently running Opus en G.722 codecs only.

Thank you very much!

 

[Intell1gence]

Stupid me, TLS is working, forgot to change the port to 5061

 

[Vince0]

Opus can be quite network tolerant. Usually G729 is the go to but it's more compressed than G722 so uses less bandwidth but generally less network tolerant. The last mile link (LTE/fibre) is the only variable with quality/reliability.