SSH on linux SBC when ISP link is 4G

[AWS2P]

Hi,
i'd like to know if you already had to use a SBC behind a 4G internet access with no static public IP.

Do you have a way to connect easily to SBC in case of need?

is it possible to add a piece of software as SBC be initiator of a connection to be available for remote manager ? ssh ?

Any advice greatly appreciated , thanks for shared experience.

 

[eddv123]

I had a similar question from a client yesterday, my response as always (and this is purely in my opinion from experience) is the VoIP over anything WiFi is not a good option (with possibly the exception of satellite connection).

You could argue that the 3CX Apps use 4G to make calls but consider that this is a single 2 way calls as opposed to using an SBC which has a potential for 100 extensions.

Also consider that if DNS resolution or connection were to fluctuate the SBC would drop the tunnel connection. What was the reason for using 4G over wired ? is it due to geographic reasons ?

Access to site for Linux machines is always the big question and one we have debated previously, I prefer Linux for stability reasons on PBX and SBC, however for access your options are:

• SSH remotely (again you have said the dynamic IP will be an issue)
• Get a little NUC for site access.
• Hook up a VPN connection to site.

 

[Clément Rousseau]

Hi aws2p!

as you are in France, you probably know that lot of fai start selling massively 4g boxes with static ip. Why not use one with static ip ? (if you are not linked to a big fai and dont have good prices on it, ask me in pm, I can give contact of commercials agents here).

Anyways we don't trust theses 4g connexions, some traffic is block or limited with theses 4g boxes (like ftp for exemple) we never know exactly how is traffic restricted or will be in future.We only use them in emergency cases or for a backup link (and even for theses cases, we prefer to set up an xdsl link if possible).

In fact to answer your question more precisely, we secure 4g access with a firewall, then we can control sbc via vpn with the firewall or ssh (restricted to office ip ofc). It works well even without static ip. But static ip is required for us if we put a 3cx on premise with a trunk (trunk provider need static ip).

 

[Zol]

Usually mobile providers assign a static IP to 3G/4G/5G connection based on the tower cell you are connected. If 1000 users are connected to the same cell tower, all of them will use the same private IP.
Some providers (speaking for Switzerland) offer a business option to activate a public IP address (usually dynamic) for your mobile connection. This is completely up to the provider to offer such an option or not.

Then, with DNS services like no-ip or dyndns you can setup your own hostname, and do portforwards on your router.

Best solution: VPN

 

[Alphabetic]

Carrier NAT is a pain especially if you want to port forward. We had an EE 4G router where it was just not possible and we had to purchase a 2nd box to use which would a) give us a static address and b) allow us to port forward. We didnt go down this route in the end. What about VNC for the Pi?

 

[AWS2P]

Thanks for your answers, if i was asking advices it's because at this location it's no other way to have a good land line with bandwith.
Fiber cost an arm or an eye (which one you prefer ) so this is not an option, land line provide poor ADSL only and plus at this location there's no more free copper available .

So only enough good option for me is to use 4G router as tower cell is only 800 m from client site. so i can use a link with almost 30Mb/s both ways.

Of course router receive only private nated ip from tower cell and that ip can change perhaps 2 or 3 times a day.

when i asked for a piece of software to add, I know it is not a supported way but when there's no other choice.
For this client PBX is on OVH cloud and sbc has 12 phones to handle

 

[eddv123]

land line provide poor ADSL only

Not sure if it is helpful for France but in the UK when we have ADSL you can upgrade it to Annex M which give or take provides enough bandwidth for around 10 simultaneous calls.

 

[AWS2P]

Hi Edd,
don't know what annex M is , not sure if it is something existing for France. If almost copper pair was available using SDSL with 2 or 4 pair of copper could be an option but unfortunately it's not.

 

[AWS2P]

Have found explaination about what annex M is, but in France it's not granted by ARCEP (regulation authority)

 

[eddv123]

Have found explaination about what annex M is, but in France it's not granted by ARCEP (regulation authority)

So basically you have to stick with ADSL - not good. Well if its any consolation I dont believe you can get SDSL over here now either.

 

[AWS2P]

ADSL is 800kb/s UP only so it's impossible to use with a 8 SC in G711A and bridge, audio quality will be crappy or worst

 

[eddv123]

Which explains the want for 4G modem.

And again this is based on an assumption for France have you investigated the possibility of getting a bunch of analogue lines to this location and fitting a VoIP/FXO gateway for conversion to IP. You could then use the ADSL line simply for 3CX licence connection.

Im not mentioning ISDN as like us over here I am pretty sure it is going obsolete in France too.

 

[AWS2P]

Which explains the want for 4G modem.

Yes , i didn't choose 4G by hasard, it's my only working choice there.

in France ,analog lines are not sold any more since one year, perhaps 2, and ISDN is the same since november 2019. France want to be full IP only. Strange choice but it is.
Even if commercial offer were always existing for land lines or ISDN, price for that kind of lines should be a show stopper .

It could be only a fix for lack of bandwith , but clearly when you switch for VOIP, you want to stay in same numeric world,no? and also I try to save customer money spend in communications.

If multiples telco support are added costs increase and finally Voip is no more interesting for customers than old PABX solutions they have previously.

 

[eddv123]

So the only option then it would seem is something wireless

In that case 4G modem, or you could consider a GSM gateway perhaps, 3CX do support one from beroNet:https://www.beronet.com/wp-content/uploads/2019/03/beroNet_Brochure_GSM-LTE-Gateways.pdf

 

[AWS2P]

Thanks Ed,
i've found a SFR B2B solution based on 4G but this time with static public IP and unlimited data volume