# How to configure SIP Trunks on 3CX
You’ll learn how to configure your 3CX PBX to make use of our SIP-trunk services and inbound numbers.\
**Step one**
Create a SIP-trunk at MessageBird Dashboard and make sure that you have a Domain name with an attached ACL that only includes IP-addresses. When an ACL includes username/passwords, they are obligated to use for setting up a SIP-trunk. For a detailed guide, head to this article: [SIP Trunking.](https://support.messagebird.com/hc/en-us/articles/360001836358)\
**Step two**
Log in to the management interface of your 3CX and do the following:
Go to **SIP trunks**:
* Select ‘Add SIP trunk’
* ‘Select Country’: choose ‘Generic’
* ‘Select Provider’: pick ‘Generic VoiP Provider’
* ‘Main Trunk No’: enter your default number that you want to display, in the international format including a leading + sign. For example +31123456789
* Click the ‘Ok’ button when ready.
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Go to the tab page **General:**
* Enter a name for your Trunk. This is for your reference only, so pick a name that will be easily identifiable for you.
* Registrar/Server/Gateway Hostname or IP’: enter the domain name that you created at the MessageBird portal
* **‘Outbound Proxy’**: enter the domain name that you created at the MessageBird portal again
* ‘Type of Authentication’: this can stay on ‘Do not require - IP Based'
* ‘Authentication ID’ (SIP User ID): leave it empty.
* ‘Authentication Password’: leave it empty.
* ‘3 Way Authentication Password’: don’t set.\
Keep in mind that other settings can be changed based on your own preference. Click the ‘Ok’ button when ready.\
Go to the tab page **DIDs:**
* Click ‘Add DID’ and enter your DID in international format Without a leading + sign (for example 31123456789) and repeat for all your DIDs. Click the ‘Ok’ button when ready.\
Go to the tab page **Caller ID:**
* At the selection **Outbound** add 2 replacement rules click ‘Add’
* Source Pattern 0 and Replace Pattern 31
* Source Pattern 00 and Replace Pattern +
* Click the ‘Ok’ button when ready.\
Go to the tab page **Options:**
* At selection ‘Advanced’, select ‘Support Re-invite’, and disable ‘Force invites to be sent to IP of Registar’
* At selection ‘Codec Priority’, remove the codec G729
* Click the ‘Ok’ button when ready.\
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\* You don’t need to change anything on tab page **Inbound Parameters.**
Go to the tab page **Outbound Parameters:**
* By default the Caller ID from Extension settings are used in case of Call forwarding to outbound calls; however, in case you want to see the original caller ID of the dialler with ‘Call Forwarding’, you need to change the following details:
* Change **Display Name** to ‘Originator Caller number will be sent’
* Change **User Part change** to ‘Originator Caller number will be sent’
* Click the ‘Ok’ button after making these changes.
That’s it! You’re all set and ready.
Check out this additional information if you need it:
* Additional information for *Outbound Rules* (general settings)\
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* Additional information for *Inbound Rules* (general settings)\
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* Additional information for *Extensions* (general settings)\
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