The invoice template is a specially formatted HTML document, which is created using either the PortaBilling layout designer or an external tool (e.g., any third-party HTML editor). We suggest generating large invoices (hundreds of pages and more) using the external template uploaded into PortaBilling as it requires less computing power for .pdf file generation in comparison with the layout designer. See the following chapters for a detailed description for each approach. It defines how the invoice should look, with information on fonts, colors, pictures, and placement of the components. When you view the invoice on the web interface, or when the invoice is automatically emailed to the customer, the template engine takes the invoice template and simply fills in the data fields (such as Header.Invoice Number) with their real values (for example, 1001 as the invoice number). The result of this processing is a .pdf file.
PortaBilling generates PDF invoices using PrinceXML – industry-leading PDF generation software. The license for PrinceXML is provided as a part of an OEM agreement for all PortaOne customers.
Requirements for invoices vary greatly from country to country (and even within the same country). The default invoice templates supplied with the system are suitable for British Columbia, Canada, and are provided as examples only. Be sure to create your own invoice template and assign it to your customers.
Three predefined invoice templates for Layout Designer are supplied with PortaBilling: “Totals only”, “Service usage details included” and “Service usage details + subtotal per service.” What is the difference between them?
A Totals only invoice
This is a traditional-style invoice. It consists of a single page with an invoice header (your company name, customer name, etc.), invoice fields (invoice number, invoice date), and invoice footer (subtotal, total).
Service usage details included invoice
This template’s first page is identical to the Totals only invoice template. In addition to this, it contains multiple pages with details of calls related to the invoice. You can use the 
Details Page button in Layout Designer to switch between the main page and the call details page. All of the calls made by a customer can be included, or only the summaries.
Service usage details + subtotal per service invoice
In addition to details of services used, this invoice contains subtotals calculated per every service.
