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What is the magic behind Provisioning and SBC?

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Andriy

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Hello, everyone,

I think this might be not an easy question, but, why do we need provisioning and 3cx SBC for connecting multiple remote phones (especially not supported) ?

Before upgrading to 3cx, I was using many other cloud PBXs (not sure if I am allowed to mention names here). And they were all inferior in versatility and performance, except one thing - you could connect ANY sip device and ANY softphone, just by inputting SIP login, SIP password and SIP ip address or domain name.

Why isn't it the case with 3cx? Why 3cx can only support certain phones and need SBC tunneling to make it happen for non-supported?

I understand that I probably will receive some answers like "Just do it the right way with supported phones because it just works", but I am interested in technical side of this.

I can register with STUN on 3cx with supported and unsupported phone, but unsupported one will drop connections or become unstable, cause one side audio etc.
This never happened with other cloud PBXs, (even though they had other problems like audio quality, caller ids, latency etc)

Please help me with my self education :)
 
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The 3CX SBC also adds encryption and security- all calls are send down the 3CX tunnel which masks the VoIP traffic.

It was historically known that some public networks were unfriendly to VoIP traffic and some even blocked it.

There are also less ports required to be opened on the firewall as well with the SBC again offering better security.
 
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Thank you fore your replies.

Well, in understand all the benefits of SBC.Few questions still remain though

1) If I have 20 supported phones connected with STUN (all on same SIP port) and everything works just fine, should I still consider adding SBC for even better performance and stability? or "aint broke dont fix it" rule applies?
If this setup is incorrect - than how come it works for so long for so many phones and calls?


2) how technically unsupported phones are different, and why I can not achieve same result with unsupported phones?

3) Before upgrading to 3CX i tried many other cloud PBXs and they all worked fine with unsupported phones connected via SIP (again same port). Are they better than 3cx in that one aspect? How do they technically achieve this? Do they identify each phone by MAC or by Username/Password? Or do they create a separate tunnel for each sip account and forward everything as needed on their side?
 
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If all you want is to have a phone to ring/dial/talk, then you can use any sip phone. If you want to be able to use other functions, like BLF's, conferencing, transfer, caller ID display - then the burden of programming the phone becomes a mountain of work, per phone. In those circumstances, the most practical method is to use the PBX to create and push the provisioning to the phone. In order to do that, the PBX must be able to create a custom provisioning file. Its too much to try to do this for every model of SIP phone that is out there. 3CX supports a reasonable selection of them, though. If you have a passion for an off brand, you can study 3CX's well documented provisioning method and create your own template. Your competitors will be pleased to see you take this approach, but 3CX will refuse to support their PBX if you use a custom developed template.
 
So yes, if you swapped to SBC you would probably get a better user experience I think, monitor how your STUN phones go and see what happens. The other point here is security however, unless you are using secure SIP and SRTP your connection is open on the internet.

Supported/un-supported phones have simply gone through the interoperability testing with 3CX, if your any good at writing custom templates you could write one (or adapt a similar model) for the phones you have maybe - but it would be deemed un-supported.

For SMB's I would say 3CX is the best PBX product out there on the market today. If you stick to the "supported" guidelines you will have a good experience, and price wise they are always miles ahead as well.
 
Hello

Thanks for answers!
Yes, 3cx is best for sure as I know now.

But i still would like to know some technical points of how it works to be in a better position to support my company system in future. So my unaswered questions are:

1) I am using 20 supported and provisioned phones on one remote location. All same SIP port. Is this wrong and should I change that and use SBC or assing a diffferent port or leave as it is?

2) I am unable to get unsupported Linksys ATA PAP2 to function properly. They get registered and connect fine, but one-side audio or later disconnection occurs.. This did not happen with other cloud PBXs(but they had other more serious problems). Why is that possible technically? do they have cloud SBC or identify the device in some other way than 3cx or is it commercial secret and will not be answered?

3) I am willing to learn new things, including custom templates. But I am using cloud version hsoted by 3CX and so far did not find a place where to upload the templates. I guess this might be impossible with cloud version hosted by 3cx. Please correct me if I am wrong.

4) If i decide to go SBC way - should I use Raspberry for 20 phones or buy a Mini PC with Linux or Windows installed? I assume 20 would be too much for a Raspberry - will it have enough resources?

Thank you
 
New Raspberry Pi 3 Model B+ will be fine for 20 phones (top limit), anything more than you are looking at a PC option for SBC
 
I see. I will go with a PC then to make it easier to add new phones.

How about this one:
1) I am using 20 supported and provisioned phones on one remote location. All same SIP port. Is this wrong and should I change that and use SBC or assing a diffferent port or leave as it is?
 
I see I am late to respond, but I hope this helps folks in the future. I have LOTS of experience with CISCO phones and Linksys ATAs (albeit on remote FreeSwitch PBXs). We went through a myriad of issues like you mentioned with one sided audio and losing connection for inbound calls to the phone. They were all NAT related. The 3CX SBC (pc version) we now use completely eliminates ALL NAT problems. It is super simple to install and I LOVE IT. The only rub is that PC is now critical to ALL your phones - if it gets rebooted or turned off, the phones are ALL down until it comes back.
With regard to 20 phones all on same port, that is a non-issue as they all have different IP addresses. The few times I have had issues with port numbers is 2 sip accounts on one phone on the same port, even then only behind a certain few routers. In my mind that should be problem all the time, so I always separate sip accounts to different ports on a single phone.

HTHs.
 
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Thank you very much Sean.
So I should leave 20 phones as is - unless I want to make it more secure - then I should go with SBC.

Why Linksys ATAs and CISCO ATAs have this problem? they also have each different IP and have NAT and STUN support...
 
Hi Andriy,
We use(d) SPA50xG phones and Linksys/Cisco ATAs (1xx and 2xx). Perhaps it was just our learning curve with NAT with PBX (FreeSwitch) offsite. We finally learned the "magic" combo of settings in the NAT section of the SIP tab. SBC is so much easier, especially for any nube's out there.
 
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Hey, Sean!

Yes, SBC seems so much easier. But it means Linksys/Cisco ATAs (1xx and 2xx) can be set up on the SIP tab after all? Do supported phones need same kind of settings?
 
Another feature of SBC is that traffic of extension to extension calls at remote location stays at the remote location - it does not travel from remote extension to pbx and back to other remote extension.
 
I was just coming back to say exacty what t2494 said! Thanks. That benefit should not be minimized. Keeping all local traffic off you WAN links can be tremendously beneficial.

My previous experience was all on FreeSwitch PBX. I just recalled the issues of one way audio and lost connectivity from the server to NAT'ed phones. We were able to fix the problem in the phone setup (SIP Tab, Nat Section, the "Handle VIA" choices).
Having said that, I do not think any phone could do plug and play from another subnet without SBC. That is handled by a multicast message when the phonew boots that will never reach the 3CX server without SBC. Supported phones can still specify the configuration URI (manually) to download their configuration. But, the option of booting the phone and having it automatically appear in 3CX for configuration will not exist.
 
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Thanks everyone for help. Still do not get technical side of it, but SBC seems to be the way to go.
 
I very seldom have any issues with my hosted clients. However, when I do, it is always the SBC for odd reasons. I have yet to have any other issues in months. We have access to them using our remote support portal, but it is still a black eye for us when one stops working and we have to reboot it.

I really wish that 3CX would spend some major development time on either improving the SBC or doing away with it and offer a cloud based SBC.

I am currently deploying a 3rd party SBC for new clients, but that is a lot of additional cost.
 
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Neville,

Thanky you for your input. Yes, cloud SBC would save everyone so much time. I still do not understand technical need for it, as every phone has its own SIP credentials (login and password and sip port) and could just connect directly to 3CX like it does with other cloud PBXs.

I understand, 3CX has a lot of other advantages over other cloud PBXs, i just can not understand why this one can not have s clean and simple solution.
 
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