Contribution:CustomInvoiceNumbers

From WHMCS Documentation

User contribution: Custom Invoice Numbers by Shaun (See all by this user)

Allows you to customize you invoice numbers.

Code changes / installation

http://forum.whmcs.com/showthread.php?t=13854

Features / Modifications

This allows you to have custom invoicing numbers. eg WHMCS###### this number does not change whenever an invoice is paid unlike the default Sequential invoicing option.