I have never known a hard limit, extensions are unlimited but 3CX do not list a figure for trunks on this chart: https://www.3cx.com/ordering/pricing/
You do not need to split your trunks DDI's, and if you have a block from the same provider can include them all on a single trunk - basically what I am saying is there should be no requirement for an abundance of trunks on your PBX if configured correctly.
Thanks!
One of my clients have several branch offices, so I try to find out if I configure a single trunk with all the DID's for in/outgoing calls, or 1 incoming trunk with all the DiD's and several outgoing trunk for outgoing calls or 1 in/outgoing trunk per site.
I know that having several trunk registerd with the same IP could create problems for incoming calls.
I want to be able to charge outgoing calls for each site if asked by the client.
Because you can only set one limit (in 3CX) on the number of calls per trunk group (both directions), if congestion were a concern, you might want to split incoming and outgoing into two groups. Some providers an offer better, or more "flexible" outgoing rates than the provider used for DIDs. In that case separate trunks also make sense. Outgoing Caller ID (options) must also be taken into consideration if you use a different provider.
One of my clients have several branch offices, so I try to find out if I configure a single trunk with all the DID's for in/outgoing calls, or 1 incoming trunk with all the DiD's and several outgoing trunk for outgoing calls or 1 in/outgoing trunk per site.
The first question is does the provider allow you to do this with one trunk? Also is it a IP based or Authentication based provider?
In both cases you might face issues with inbound calls if the trunks are not setup correctly so i would be very careful with the configuration.
Make sure that you are using a supported provider that will make the configuration a lot easier. https://www.3cx.com/partners/sip-trunks/
The SIP provider is Alphalink, no problem. The authentication is IP + login/password.
So OK, If there's no SIP trunk limit with 3CX, we are gonna test different configurations.
Hopefully you do not mean that your provider is IP Authenticated - IP Authentication is great for security but not very good when it comes to flexibility for configuration so you may want to re-think this one if they are.
For IP Authentication you allow your providers public IP through your firewall and they do the same at their end, I have never known anyone achieving this sort of setup with IP authenticated.
That being said there is a fudge that can be done within 3CX for the system to be able to differentiate between the two trunks in a failover situation, this may offer some hope.
For failover with IP Authenticated (I know resellers using this for GAMMA here in the UK)
you will need to put a "fake" Authentication ID in your trunks - under Authentication ID (aka SIP User ID). This should be different to each trunk. E.g. first trunk authentication ID 12345 second trunk 45678.
If you want more information on this setup I have some notes somewhere so can dig them out if you want to give it a go.
The SIP provider is Alphalink, no problem. The authentication is IP + login/password.
So OK, If there's no SIP trunk limit with 3CX, we are gonna test different configurations.
If the provider is authentication based then you might have an issue registering multiple instances of the same trunk.
If that is allowed and your provider supports rinstance then multiple accounts might work.
Let us know what you find
