Running two PBX at the same time - progressive migration to 3CX

[SimonLessard]

Hello everyone!

We are currently running on an old Toshiba PBX where 4 SIP trunks are delivered to it. I'm currently testing the 3CX platform on the side and it is going well. The thing is that, for some reasons I cannot just order new SIP phones for everyone right away and get rid of the Toshiba. And I cannot use Toshiba's phone on 3CX since they are running on a proprietary protocol, not supporting SIP. I need to add new extensions to my network but the Toshiba is at full capacity. What I would like to do is the following :
- Setup my 3CX with all my new Grandstream phones will report to this PBX and allow internal calls (calls to my local 1xx extension)
- Keep my Toshiba running with all the extensions that needs to make call outside and inside
- Be able to call 1xx extension from the phones on the 3CX PBX to phones on the Toshiba PBX and vice versa
- Live happy with this for 6 months until we get all new phones and move 100% 3CX! (That part is easy...)

Is there a way to do that?
The best of the best would be to be able to call external numbers and receive call on both PBX with the same 4 trunks but I think this is just not possible to share SIP trunks...

Thanks!
Simon

 

[leejor]

No, it probably isn't going to be possible to share your trunks between the two systems.

Personally, I would wait until i had all of the necessary phones, then do a full cut. You can do configuration and testing on the 3CX PBX in the meantime, of course. But, save the cut until everything is ready to go. It is going to be a real mess trying to have two system working partially in parallel, and really, not much of a benefit.

 

[Andyshawn]

If I understand you correct, you said that the Toshiba has 4 SIP Trunks terminating on it. If that is the case, why don't you try creating a SIP Trunk between the 3CX and the Toshiba?
Once you have that Trunk in place, then you can just create dial rules to call between the Toshiba and 3CX.

I have a similar setup with one of my major clients, but they have Avaya IP Office and I integrated that with 3CX. Right now i've setup 30 Yealink IP phones on the 3CX system and over 100 extensions still active on the Avaya IP Office and we are able to make calls both ways, so the testing is going great. Testing will continue for another few months, then we will do a full cutover to 3CX.

 

[Wendelspanswick]

We have similar sites, legacy phone systems with a partial intergration of 3CX systems.
We have a 3CX with a sip link to a Mitel 3300. Calls out and in to the 3CX are routed through the Mitel using the Mitels SIP trunks.
And we have an Siemens ISDX that routes through to a 3CX via a a PRI card and a Patton gateway, this 3CX has it's own SIP trunks but can also dial out over the link to the ISDX and then out on the ISDN30 lines on the ISDX.

 

[SimonLessard]

Those two scenarios your presented are pretty much what I would like to do! Thanks for sharing this.
I didn't know that I could configure a PBX to act as a "trunk server"? How to create that SIP trunk betweek the two PBX?

 

[Wendelspanswick]

For the Mitel to 3CX I set up an internal SIP trunk between the 3CX and the Mitel PBX using the Generic Template, then created rules so that when you dial the other systems extension numbers it uses this link. Make sure you can dial between the two.
Then I added a rule on the 3CX so that when users dial 7xxxxxxxxxxx it uses the link but does not strip any digits.
The Mitel see's 7xxxxxxxxxxx which matches the rule for the external SIP trunk, it strips the 7 and dials out.
I then route specific incoming DDI numbers on the Mitel to use the link to the 3CX.

 

[leejor]

If you want to bridge the two PBXs, then you can follow this guide.

https://www.3cx.com/docs/

 

[Andyshawn]

For the Mitel to 3CX I set up an internal SIP trunk between the 3CX and the Mitel PBX using the Generic Template, then created rules so that when you dial the other systems extension numbers it uses this link. Make sure you can dial between the two.
Then I added a rule on the 3CX so that when users dial 7xxxxxxxxxxx it uses the link but does not strip any digits.
The Mitel see's 7xxxxxxxxxxx which matches the rule for the external SIP trunk, it strips the 7 and dials out.
I then route specific incoming DDI numbers on the Mitel to use the link to the 3CX.

My setup was very similar to this which you have described and I have calls routing from the 3CX extension through the Avaya IP Office PRI Lines and out to the PSTN that are connected to the Avaya system. My Outbound rules are 9XXXXXXXXXX and it chooses the AvayaRoute to place external calls.

 

[eddv123]

As @Wendelspanswick has suggested, using a Patton for a slow migration is a viable option.

These devices are not like your standard legacy to IP converter gateways, they are very flexible and offer options which should be able to give you a smooth migration process and are pretty much the only "supported" gateway brand who would be able to achieve this.

Here are some links which should be of interest:
https://www.patton.com/whitepapers/sip_trunking_white_paper.pdf
https://www.patton.com/solution/Legacy-Voice-Connectivity/

Note: you will need a competent Patton engineer to configure this however their support is very good and should be able to assist if the requirement comes into fruition.