Sync Invoice Numbering for Multiple WHMCS Installations

Invoice Numbering for Multiple Stores

If you're running multiple installations of WHMCS, you might need to issue invoices with sequential numbering. This is not possible as each WHMCS follows its own numbering sequence but thanks to our modules you don't run our of options.

The first option you have is using Mercury that lets you configure multiple domains on WHMCS. This also reduces costs as you don't need maintain multiple installations and makes things easier to manage.

The second option is to use the in-built Invoice Sync of Billing Extension. The module creates a "link" between all your systems. Every time an invoice or credit note is issued, the module sync sequential numberings on all the involved WHMCS.

Let's suppose you have 3 WHMCS: blue, red and orange. Next invoice ID is set to #50 on all systems. At some point "blue" WHMCS issues invoice #50. Billing Extension automatically increases Next ID to #51 on "red", "orange" and of course "blue".

This grants that all invoices and credit notes follow sequential numbering, no matter how many WHMCS you are using. It is worth to say that Invoice Sync and respects your WHMCS billing settings. You don't have to worry about anything.

Invoice Sync Requirements

A copy of Billing Extension (2.2.8 or newer) must be installed on all your WHMCS. The following settings on Addons > Billing Extension > Settings must be equal on for all systems:

• Invoices > Next ID
• Invoices > Increment
• Credit Notes > Dedicated Sequential Numbering
• Credit Notes > Next ID
• Credit Notes > Increment

Please, be very careful when you edit these fields as you could break the synchronization. If you need to make changes to any of these parameters, repeat repeat the operation for all systems.

Configuring Invoice Sync

Invoice Sync is possible thanks to a Webservice integrated in Billing Extension. To secure connection between all your installations of WHMCS, generate a token from Addons > Billing Extension > Settings > Invoice Sync > Token.

Such token must be the same on all your systems. Once done, focus on Addons > Billing Extension > Settings > Invoice Sync > Systems. Here you have to insert the System URL of all WHMCS (one per line) as follows.

To avoid any possibility of confusion, the System URL is the one you find in Setup > General Settings > WHMCS System URL. Repeat the process on every WHMCS.

If something goes wrong, Billing Extension notifies about sync issues from the in-built warning system that is also used to detect billing errors.