Why VoIP Security Matters
VoIP phone systems, like any network-connected technology, can be targeted by malicious actors. Understanding the threats and implementing proper security measures is essential for protecting your business communications.
Common VoIP Security Threats
- Eavesdropping: Unauthorized interception of voice calls to capture sensitive business conversations or confidential information.
- Toll Fraud: Attackers gaining access to your phone system to make expensive long-distance or international calls at your expense.
- Denial of Service (DoS): Overwhelming your VoIP infrastructure with traffic to disrupt phone service availability.
- Unauthorized Access: Hackers accessing voicemail, call recordings, or administrative controls to steal data or modify system settings.
Best Practices for VoIP Security
1. Use a Separate VLAN for Voice Traffic
Segment your voice traffic from regular data traffic by placing all VoIP devices on a dedicated VLAN (Virtual Local Area Network). This isolation:
- Prevents data network issues from affecting phone service
- Limits the attack surface for potential intruders
- Improves Quality of Service (QoS) by prioritizing voice packets
- Makes it easier to apply specific security policies to voice traffic
2. Implement Strong Authentication
Enforce robust password policies across your VoIP infrastructure:
- Use complex passwords for SIP registration (minimum 12 characters with mixed case, numbers, and symbols)
- Change default passwords on all phone devices immediately upon deployment
- Require strong voicemail PINs (avoid simple patterns like 1234 or 0000)
- Implement two-factor authentication for administrative access where possible
3. Encrypt Voice Traffic
Enable encryption to protect calls from eavesdropping:
- SIP over TLS (Transport Layer Security): Encrypts the signaling (call setup) portion of VoIP communications
- SRTP (Secure Real-time Transport Protocol): Encrypts the actual voice media streams
IntelliVoice supports both TLS and SRTP encryption. Contact support to verify encryption is enabled on your account.
4. Restrict Network Access
Limit which IP addresses and networks can communicate with your VoIP devices:
- Configure access control lists (ACLs) to allow only trusted IP ranges
- Block SIP traffic from countries where you do not do business
- Use your firewall to restrict inbound SIP ports to known provider IP addresses
- Disable remote phone provisioning if not required
5. Keep Firmware Updated
Regularly update your VoIP phone firmware to patch security vulnerabilities:
- Check manufacturer websites for firmware updates quarterly
- Test updates in a non-production environment before mass deployment
- Maintain an inventory of all devices and their firmware versions
Note: IntelliVoice manages firmware updates for phones provisioned through our platform. We handle testing and deployment of security patches automatically.
6. Disable Unused Services
Reduce your attack surface by disabling features you do not use:
- Turn off web interfaces on phones if not needed for management
- Disable SSH/Telnet access if not required
- Remove or disable unused SIP accounts on devices
- Disable multicast and CDP/LLDP if not used for provisioning
7. Monitor Call Logs and System Logs
Regularly review logs for signs of suspicious activity:
- Watch for unusual call patterns (high volume of international calls, calls at odd hours)
- Monitor for repeated failed authentication attempts
- Set up alerts for calls exceeding certain durations or costs
- Review registration logs for unknown devices or IP addresses
Note: IntelliVoice provides real-time monitoring and automated fraud detection for all hosted customers. We proactively alert you to suspicious activity.
8. Use a VoIP-Aware Firewall
Standard firewalls may not properly handle VoIP protocols. Use a firewall that:
- Understands SIP and RTP protocols
- Can perform deep packet inspection on voice traffic
- Properly handles NAT traversal for VoIP
- Can be configured with SIP-specific security policies
Important: Be cautious with SIP ALG (Application Layer Gateway) settings on your firewall. While intended to help, SIP ALG often causes more problems than it solves and should typically be disabled.
IntelliVoice Security
As an IntelliVoice customer, many security measures are handled on your behalf:
- Firmware updates and patches are managed by our team
- 24/7 monitoring for toll fraud and suspicious activity
- Encryption options for signaling and media
- Secure, redundant data centers with physical access controls
- Regular security audits and penetration testing