diff --git a/README.md b/README.md
index 1186a697..0cb40e23 100644
--- a/README.md
+++ b/README.md
@@ -392,12 +392,12 @@ _[IRC](https://en.wikipedia.org/wiki/Internet_Relay_Chat) communication software
 _[SIP](https://en.wikipedia.org/wiki/Session_Initiation_Protocol) telephony software_
 
 - [Asterisk](http://www.asterisk.org/) - Easy to use but advanced IP PBX system, VoIP gateway and conference server. `GPL-2.0` `C`
+- [ASTPP](https://www.astppbilling.org/) - is an Open Source VoIP Billing Solution for Freeswitch. It supports prepaid and postpaid billing with call rating and credit control. It also provides many other features. ([Source Code](https://github.com/iNextrix/ASTPP)) `AGPL-3.0` `PHP`
 - [FreeSWITCH](https://freeswitch.org/) - Scalable open source cross-platform telephony platform. ([Source Code](https://freeswitch.org/stash/projects/FS/repos/freeswitch/browse)) `MPL-2.0` `C`
 - [Homer](https://www.sipcapture.org/) - Troubleshooting and monitoring VoIP calls. ([Source Code](https://github.com/sipcapture/homer)) `AGPL-3.0` `Angular/C`
 - [Kamailio](http://www.kamailio.org/w/) - Modular SIP server (registrar/proxy/router/etc). ([Source Code](https://github.com/kamailio/kamailio)) `GPL-2.0` `C`
 - [Ostel](https://dev.guardianproject.info/projects/ostel/wiki/Server_Documentation) - Secure SIP telephony setup with ZRTP encryption. `GPL-3.0` `Ruby`
 - [Tapir](http://www.sip3.io/) - Troubleshooting and real-time monitoring of VoIP-based systems. ([Source Code](https://github.com/sip3io/tapir)) `Apache-2.0` `Java/Kotlin`
-- [ASTPP](https://www.astppbilling.org/) - is an Open Source VoIP Billing Solution for Freeswitch. It supports prepaid and postpaid billing with call rating and credit control. It also provides many other features. ([Source Code](https://github.com/iNextrix/ASTPP)) `AGPL-3.0`
 
 ### IPBX