diff --git a/voice-client/files/etc/firewall.sip b/voice-client/files/etc/firewall.sip
index f09f7b642..5715b4b2c 100644
--- a/voice-client/files/etc/firewall.sip
+++ b/voice-client/files/etc/firewall.sip
@@ -1 +1,6 @@
-iptables -I zone_wan_input 4 -m udp -p udp --dport 10000:20000 -m comment --comment "!fw3: Allow-RTP" -j ACCEPT
+rtpstart=$(uci -q get voice_client.SIP.rtpstart)
+rtpstart=${rtpstart:-10000}
+rtpend=$(uci -q get voice_client.SIP.rtpend)
+rtpend=${rtpend:-20000}
+
+iptables -I zone_wan_input -m udp -p udp --dport $rtpstart:$rtpend -m comment --comment "!fw3: Allow-RTP" -j ACCEPT