diff --git a/README.md b/README.md
index 2c69cc3..2978291 100644
--- a/README.md
+++ b/README.md
@@ -258,8 +258,9 @@ Any other questions? Please check out our [FAQ](./FAQ.md), and if your question
     * [Version Control Servers](#version-control-servers)
   * [Virtualization](#virtualization)
   * [Volunteer Computing](#volunteer-computing)
-  * [VoIP software](#voip-software)
-    * [VoIP servers](#voip-servers)
+  * [VoIP Software](#voip-software)
+    * [SIP Servers](#sip-servers)
+      * [Alternatives](#sip-server-alternatives)
   * [VPN Software](#vpn-software)
   * [Whiteboard](#whiteboard)
   * [Window Managers](#window-managers)
@@ -2766,15 +2767,22 @@ Volunteer computing is a system in which someone can donate (excess) compute res
 |---|:---:|---|---|
 | [BOINC](https://boinc.berkeley.edu/) | [`3e5c24b`](https://github.com/BOINC/boinc/commit/3e5c24b6ed0fdf66ae0e7814c9d9ebc994fb3b01) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/BOINC/boinc/commit/95cf8aa6c4cfaa5cb2ead01f6161290f0c1fa2ac), [2](https://github.com/BOINC/boinc/commit/efba32432d383732249b6171acdba3799b02da65), [3](https://github.com/BOINC/boinc/commit/ea17911ab1fe8b5b0167c47c46d9d2297d2eb501))<br />[![AI Code Reviews](./badges/ai-code-reviews-purple.svg)](#ai-code-reviews) ([1](https://github.com/BOINC/boinc/pull/5914), [2](https://github.com/BOINC/boinc/pull/5918), [3](https://github.com/BOINC/boinc/pull/5954)) | [![Request for Help](./badges/request-for-help.svg)](#request-for-help) |
 
-## VoIP software
+## VoIP Software
 
 Voice over IP software permits making telephone calls over an IP network. It can be considered a sort of [internet messaging](#messaging).
 
-### VoIP servers
+### SIP Servers
 
-| Name | Last Untainted <br />Version/Commit ID | Tags and Evidence | Alternative(s) |
-|---|:---:|---|---|
-| [Kamailio](https://www.kamailio.org/w/) | [`86549be`](https://github.com/kamailio/kamailio/commit/86549be22f92442c192281bedcce1c3a1f80cac1) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/kamailio/kamailio/pull/4640), [2](https://github.com/kamailio/kamailio/commit/79f5265057c99a6058bb92a3c0992fa1b9b0c121)) | [![Request for Help](./badges/request-for-help.svg)](#request-for-help) |
+SIP, or Session Initiation Protocol, is a signaling protocol used to start, manage, and end communication sessions such as voice calls, video calls, and messaging.
+
+| Name | Last Untainted <br /> Version/Commit ID | Evidence |
+|---|:---:|---|
+| [Kamailio](https://www.kamailio.org/w/) | [`86549be`](https://github.com/kamailio/kamailio/commit/86549be22f92442c192281bedcce1c3a1f80cac1) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/kamailio/kamailio/pull/4640), [2](https://github.com/kamailio/kamailio/commit/79f5265057c99a6058bb92a3c0992fa1b9b0c121), [3](https://github.com/kamailio/kamailio/blob/master/.github/PULL_REQUEST_TEMPLATE.md)) |
+| [Routr](https://github.com/fonoster/routr) | [`v2.13.21`](https://github.com/fonoster/routr/releases/tag/v2.13.21) <br /> [`a0674f5`](https://github.com/fonoster/routr/commits/a0674f5ade2c8af48e289dbd79ec63bcd1622df5) | [![Permissive AI policy](./badges/permissive-ai-policy-orange.svg)](#permissive-ai-policy) ([1](https://github.com/fonoster/routr/blob/main/.claude/kaizen/log.md), [2](https://github.com/fonoster/routr/commit/bdf27cf3bc06bf5deff198883299f4ad2703ee40), [3](https://github.com/fonoster/routr/commit/1c7242defaf4fce49565b92c87bc6b4be8cda715)) <br /> [![AI Code Reviews](./badges/ai-code-reviews-purple.svg)](#ai-code-reviews) ([1](https://github.com/fonoster/routr/pull/354#event-28404149301)) |
+
+> [!NOTE]
+> #### SIP Server Alternatives
+> * [Flexisip](https://github.com/BelledonneCommunications/flexisip)
 
 ## VPN Software