Use and feel our experience and expertise to keep your business secure.Unified communications introduces specific security risks. Organizations needs to take countermeasures to prevent vulnerabilities. Integration of all voice, data and video communications to a common network means that the unified communication networks are no more secure. There are some threats and avenues of attacks which are specific to UC communications or the applications on the platforms.

A top concern is that unauthorized interception of VoIP, IM or other traffic. UC endpoints, whether desktops, laptops, or IP phones — not really phones but rather computers with specialized user interfaces — all connect to the data network, and can be tapped by compromising the network anywhere along the data route.  Moreover, it has become possible with hard or softphones, once they are compromised, to have their conferencing or handset/headset microphones activated without being taken off the hook. This enables remote eavesdropping on private conversations taking place in person, and often behind closed doors. Performing such compromises may not be easy, but the changing nature of security attacks — from amateur to professional, from general to targeted — means that these techniques will be developed and available to anyone for a price.

A related fear is toll fraud. IP telecommunications providers around the world lose hundreds of millions of dollars annually due to stolen services, especially long-distance services. Unified communications voice and video traffic typically now use the Session Initiation Protocol (SIP) to control calls, but the actual media stream for a call is separate from that control stream. It is possible, therefore, to use SIP to perpetrate a new kind of toll fraud. An attacker can use SIP to lie to the call manager about what kind of call it is controlling. For example, the perpetrator might tell the call manager that a call will be voice-only, but then stream high-definition video instead, essentially defrauding the system owner of the higher revenues for the video traffic.

Cisco Unified communications security lifecycle has various components to achieve the required end to end security .


Designing and implementing a secure Unified communication infrastructure has many components:

IP telephony Risk Assessment

Within the context of IP telephony pertinent to business processes, converged voice and data IP networks are entrusted to carry sensitive information and the essential functions of conducting business to and from the employees, vendors, and partners. Essentially it’s an ecosystem which requires end-to-end security. And in doing so, an IP telephony network must be secured in such a way that:

  • It complies with applicable laws and regulations
  • It protects intellectual property and proprietary information
  • It upholds expectations from corporate reputation viewpoint

Fundamentally, neither an IP telephony solution by-itself be assumed to mitigate all security risks nor should network security measures be assumed to be enough to thwart all threats on their own. A defense-in-depth approach is required to curb and evade potential threats, which can be build aided by a comprehensive risk mitigation strategy blended with network layer and application layer security measures.

According to Cisco, “The primary objective is to integrate IP telephony and traditional data services onto a converged network infrastructure, without compromising the security of either service.”

Thus, layered security approach (defense in depth) for implementation of security controls in a holistic manner in an enterprise or organization lays down a solid foundation to build a secure and robust IP telephony solution. The security solution should be layered, with multiple controls and protection at multiple network and application levels. This minimizes the possibility of a single point of failure leading to a compromise in overall security construct.

The desired end result is that the confidentiality, integrity, and availability of critical IP telephony applications and network resources must be ensured while maintaining the solution’s performance. In a nutshell, security should be transparent to the user, simple to administer, cost‐effective, and standards‐based.

The first step toward securing a Cisco IP telephony solution is to gain an understanding of the risks involved. Pertinent to IP telephony, security risks can be broadly categorized as follows:

  • Interception and impersonation of IP telephony voice and signaling sessions leading to loss of confidentiality or integrity or both
  • Non-authorized or fraudulent use of IP telephony equipment or services for example, toll fraud
  • Denial of Service (DoS) or Distributed DoS attacks, leading to degradation of voice services

Direct/Indirect intrusion of other services associated with or facilitated by the IP telephony implementation

IP Telephony Security Strategy

A security strategy/policy gives direction to efforts, resources, and security controls or mechanism such that an organization can focus on the where, what, how, why, and when aspects of deploying security for its IT infrastructure. Same goes for IP telephony as well, since Cisco IP telephony is established not just by applications, rather by devices and infrastructure, which applications leverage for their operation. Hence, a systemic approach helps ensure that directional efforts account for resources, and planned controls are in line with business objectives.

When it comes to IP telephony—like any other discipline of networking—rather than implementing security post deployment, it’s a good idea to ensure that security goes with IP telephony planning and design i.e. security is a coherent part of PPDIOO phases in a Cisco IP telephony deployment project.


Security strategy will differ for different businesses or organizations as per their risk appetite and the requirements from business verticals. For example, a school may not require all endpoints to be authorized before being admitted in the network (Network Access Control); however, for a government organization this might be a norm. Hence, once size fits all doesn’t work with security strategy/policy development. A security strategy for an IP telephony solution may be developed based on following elements (not all inclusive or exclusive):

  • Acceptable usage, behavior, and conduct pertinent to telephony resources/system
  • Physical security measures
  • Network infrastructure security
  • Perimeter access security
  • Server hardening
  • Definition of secure and non-secure zones
  • User endpoint security
  • Wireless infrastructure security
  • Vendor, partner, and consultant access restrictions
  • Back and restore (including disaster recovery) security
  • Network management and security response
  • Internet access
  • Lawful interception of calls

Deploying Secure Cisco IP telephony Networks

The attacks on IP telephony systems can be broadly categorized into the following types:

  • Confidentiality/Privacy which includes (not limited to) voice call eavesdropping, hijacking sessions
  • Integrity/Authenticity which includes (not limited to) impersonization, injection
  • Availability which includes (not limited to) DoS/DDoS, network infiltration
  • Theft which includes (not limited to) toll fraud, data theft
  • Spam over Internet Telephony (SPIT) which includes (not limited to) unsolicited calling

With a wide variety of potential threats and attacks, no solo mechanism can curb the otherwise imminent threat. Henceforth, a notion multilayer security approach (is not an option but a necessity.

To achieve end-to-end security, everything right from a user endpoint to peripheral gateways to firewalls to physical access should be secured.


Recommended best practices and recommended security controls to design and deploy a secure Cisco IP telephony networks can defined a below

Layer 1 (Physical Layer) Security

  1. Badged access to data center and other facilities. Guards at data center or facility periphery
  2. Alarms and sensors at data center periphery and entry/exits
  3. Appropriate arrangements for fire extinguishing
  4. Automatic doors with break proof glass
  5. CCTV cameras where required (and possible)
  6. Equipment secured in racks in data center and in closets at user access level
  7. Role based access (authorization) to IP telephony/network equipment
  8. Uninterrupted Power Supply (UPS) for servers and network devices

Layer 2 (Switching Layer) Security

  1. Segregation of data and voice VLAN
  2. Application of port based security where possible
  3. Dynamic ARP inspection
  4. DHCP snooping
  5. Limited MAC addresses per physical switch port
  6. Layer 2 ACL’s (where possible)
  7. Layer 2 QOS to differentiate between priority, default, and scavenger traffic (where possible)
  8. Network Access Control (NAC)
  9. VLAN pruning
  10. Secure management access to switch interface (SSH)

Layer 3 (Routing Layer) Security

  1. Routing protocol authentication
  2. Secure access to router console, VTY (SSH)
  3. Secure access to router GUI (HTTPS)
  4. uRPF
  5. Filtering of RFC 1918 addresses (at aggregation from untrusted networks)
  6. Secure Hot Standby Routing Protocol (HSRP) (where applicable)
  7. Route poisoning prevention
  8. Layer 3 QOS for segregating intended traffic from scavenger/malicious traffic
  9. Layer 4 -7 (LAN/WAN/Perimeter) Security
  10. Cisco ASA Firewalls to broker connection from untrusted zone to trusted zone (filtering TCP/UDP connections)
  11. Internet or extranet facing servers to be placed in DMZ
  12. Network Intrusion Prevention System (NIPS) to inspect and filter/drop packets/sessions as malicious packet content
  13. IPSec/SSL VPN based off Cisco ASA Firewall and IOS routers
  14. UC proxy services (TLS proxy/Phone proxy)
  15. Deep packet scanning (inspect)
  16. Rate limiting by Application Inspection Control (AIC)

IP telephony Server Security (Call Control)

  1. Secure communications by virtue of Certificate Authentication Proxy Function (CAPF)—TLS for signaling and SRTP for media
  2. Secure access to GUI (HTTPS)
  3. Secure CTI/JTAPI
  4. Secure LDAP integration
  5. Secure voicemail integration
  6. Secure presence integration
  7. Secure SIP Trunks
  8. Integration with external certificates (Third Party PKI chain)
  9. Integration with industry standard SSO solution
  10. Host Intrusion Prevention System (HIPS)—CSA/SELinux
  11. Role based management and user access

IP telephony Server Security (Voicemail)

  1. Secure communications with endpoints—TLS for signaling and SRTP for media
  2. Secure integration with call control
  3. Secure access to GUI (HTTPS)
  4. Secure LDAP integration
  5. Integration with external certificates (Third Party PKI chain)
  6. Secure voice messaging (private messages)
  7. Integration with industry standard SSO solution
  8. HIPS
  9. Role based management and user access

IP telephony Server Security (Presence)

  1. Secure communications with endpoints—TLS for signaling and SRTP for media
  2. Secure integration with call control
  3. Secure access to GUI (HTTPS)
  4. Secure LDAP integration
  5. Integration with external certificates (Third Party PKI chain)
  6. HIPS

IP telephony Server Security (Contact Center)

  1. Secure integration with call control
  2. Secure recording
  3. Secure endpoints for agents
  4. Secure recoding
  5. Platform security for CVP, ICM, and other windows based platforms (Antivirus, HIPS)

IP Phone Security (Wired, Wireless, and Soft phone)

  1. Secure endpoint with CAPF certificates (LSC)
  2. Secure endpoint with built-in certificates (MIC)
  3. Secure network admission (dot1x)
  4. Secure WiFi admission (WPA, WPA2)
  5. Restricted access to settings
  6. Phone hardening
  7. VPN Phone
  8. Restricted access to system registry (for softphone)
  9. Trusted Relay Point (for softphone)

IP telephony Network Management

  1. Secure access to network equipment and servers (In-Band or Out Of Band management)
  2. Secure network management protocols for example: SSH, SCP, SFTP, HTTPS
  3. Security Event Management System (SEMS) or Security Information or Event Management (SIEM)
  4. Backup and restore processes
  5. Disaster Recovery System or and Disaster Recovery Site