# Created a multi-tenant phone (VoIP) and billing system that integrates with FreeAgent for invoicing and updating contact details **URL:** \ **Category:** Uncategorized\ **Created:** [25 September 2026 23:37 UTC](https://api-discuss.freeagent.com/t/created-a-multi-tenant-phone-voip-and-billing-system-that-integrates-with-freeagent-for-invoicing-and-updating-contact-details/6785 "2026-09-25T23:37:50Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Ellwould](https://api-discuss.freeagent.com/user_avatar/api-discuss.freeagent.com/ellwould/32/1274_2.png) [@Ellwould](https://api-discuss.freeagent.com/u/Ellwould)\ **Post date:** [25 September 2026 23:37 UTC](https://api-discuss.freeagent.com/t/created-a-multi-tenant-phone-voip-and-billing-system-that-integrates-with-freeagent-for-invoicing-and-updating-contact-details/6785/1 "2026-09-25T23:37:50Z")
Created freely available open source software aimed at the IT/telecommunication industry that automatically bills for SIP extensions/seats, PBX’s and phone call minutes. The software can be run on one server and can be used to support thousands of endusers as it is designed to be multi-tenant from the ground up. It integrates with FreeAgent to allow sending invoices and updating contacts. The software is named YAP (Yet Another PBX) and the manual/guide is located at - [https://yap.ell.today](https://yap.ell.today) YAPs source code is available at - [GitHub - yet-another-pbx/yap: YAP (Yet Another PBX) - A GUI to administrate a multi-tenanted SIP Server, automatically creates invoices and connects to 3rd party accountancy software to send invoices. YAP is written in Go and uses the Asterisk framework. · GitHub](https://github.com/yet-another-pbx/yap) There is also another piece of open source software named CDR Importer specifically designed to work with YAP to import and re-rate Call Detail Records (CDRs) from a SIP trunk supplier