diff --git a/modules/clan/phonebox/default.nix b/modules/clan/phonebox/default.nix
index acfe7d6..70c53ad 100644
--- a/modules/clan/phonebox/default.nix
+++ b/modules/clan/phonebox/default.nix
@@ -111,8 +111,8 @@
 
             "rtp.conf" = ''
               [general]
-              rtpstart=10000
-              rtpend=20000
+              rtpstart=${rtpPortFrom}
+              rtpend=${rtpPortTo}
             '';
 
             "pjsip.conf" = ''