To ensure stable call quality and consistent app performance, Romulus requires specific ports, domains, and IP ranges to be allowlisted in your firewall, antivirus software, and any content filtering tools such as web proxies or IDS/IPS systems.
General configuration requirements
All Romulus apps rely on the following ports and domains. Make sure these are allowlisted in your environment.
Required ports (allow outbound traffic)
Protocol | Port or range | Function or notes |
TCP | 443 | Secure signaling and API traffic over HTTPS (Romulus app, dashboard) |
TCP/UDP | 5060 | SIP signaling (Twilio and SignalWire) |
TCP | 5061 | SIP signaling over TLS |
UDP | 10000 to 60000 | RTP media traffic for voice calls |
Required domains and URLs (allowlist)
Allowlist the following domains in your firewall, web proxy, and any content filters. The asterisk symbol covers all subdomains.
Domain or URL | Purpose |
*.romulus.live | Primary Romulus service (app, dashboard, API) |
*.twilio.com | Voice/telephony infrastructure provider |
*.signalwire.com | Voice/telephony infrastructure provider |
*.intercom.com | In-app chat and support |
*.eu-north-1.amazonaws.com | Voicemail and call recordings storage (AWS S3, EU) |
Server specific IP addresses
Romulus relies on Twilio and SignalWire for telephony infrastructure. While you may restrict traffic to specific IP addresses for tighter security, these ranges can change over time — allowlisting by domain (above) remains the most reliable option.
Important: Twilio and SignalWire IP ranges can change without prior notice. If you must use static IP ranges, check the providers' official Twilio's Network Documentation and SignalWire's Network Documentation — for the most current information.
Twilio media (RTP) — all regions
Twilio's global media gateway is identical across all edge locations (Sydney, São Paulo, Dublin, Frankfurt, Tokyo, Singapore, Virginia, Oregon, and roaming).
Purpose | IP address or CIDR | UDP ports |
Media (RTP/STUN), all edge locations | 168.86.128.0/18 | 10000 to 60000 |
Twilio SIP signaling gateways (by region)
Region | IP address range (CIDR) | Ports |
North America — Virginia | 54.172.60.0/30 | 5060 (UDP/TCP), 5061 (TLS) |
North America — Oregon | 54.244.51.0/30 | 5060 (UDP/TCP), 5061 (TLS) |
Europe — Dublin | 54.171.127.192/30 | 5060 (UDP/TCP), 5061 (TLS) |
Europe — Frankfurt | 35.156.191.128/30 | 5060 (UDP/TCP), 5061 (TLS) |
Asia-Pacific — Tokyo | 54.65.63.192/30 | 5060 (UDP/TCP), 5061 (TLS) |
Asia-Pacific — Singapore | 54.169.127.128/30 | 5060 (UDP/TCP), 5061 (TLS) |
Asia-Pacific — Sydney | 54.252.254.64/30 | 5060 (UDP/TCP), 5061 (TLS) |
South America — São Paulo | 177.71.206.192/30 | 5060 (UDP/TCP), 5061 (TLS) |
Note: Twilio does not guarantee which edge location handles signaling for a given call. For resiliency, allow all regional gateways listed above rather than a single region.
SignalWire signaling and media
SignalWire does not publish fixed IP ranges for its SIP and media infrastructure, since these can change. Allowlist by domain instead:
Domain | Purpose | Ports |
sip.signalwire.com | SIP signaling | 5060 (UDP/TCP), 5061 (TLS) |
relay.signalwire.com | Media relay (RTP) | UDP 10000 to 60000 |
Note: If your firewall requires static IP addresses rather than domains, resolve these hostnames periodically and update your rules accordingly:
dig sip.signalwire.com | egrep ^sip | awk '{ print $5 }' | xargs -n1 -I{} iptables -A INPUT -s {} -j ACCEPT
dig relay.signalwire.com | egrep ^relay | awk '{ print $5 }' | xargs -n1 -I{} iptables -A INPUT -s {} -j ACCEPT
dig firewall.signalwire.com | egrep ^firewall | awk '{ print $5 }' | xargs -n1 -I{} iptables -A INPUT -s {} -j ACCEPT
Critical call quality and troubleshooting
Adjusting UDP session timeout
VoIP traffic depends heavily on UDP. Since UDP does not use a handshake to close connections, firewalls may terminate an active call session too early. Increasing the UDP session timeout helps prevent interruptions.
ACTION: Increase the UDP session timeout on your firewall or router. The recommended value is at least 90 seconds.
Tip: If possible, apply the extended timeout only to Romulus, Twilio, and SignalWire destinations to avoid unnecessary changes to unrelated traffic.
Gateway features that affect VoIP quality
Certain gateway features can disrupt real-time media traffic and cause one-way audio, choppy calls, or dropped connections. If you experience call quality issues, try disabling or bypassing the following features specifically for Romulus, Twilio, and SignalWire traffic:
Deep Packet Inspection or Stateful Packet Inspection
Intrusion Detection or Intrusion Prevention Systems
Web proxies or web filters
WAN optimization devices
Port filtering that exceeds the required ports listed above
Packet-by-packet load balancing across multiple ISPs, since this can reorder RTP packets
Configuring your network according to these guidelines ensures the best possible performance when using Romulus.