Your VoIP phone system is one of the most exposed parts of your IT infrastructure and most businesses have no idea. Unlike a traditional phone line that required physical access to tap, a VoIP system connected to the internet is accessible to anyone in the world who knows how to look for it. Toll fraud attacks can rack up thousands of dollars in international call charges overnight. Eavesdropping on unencrypted voice traffic is straightforward for anyone with basic network access. A poorly configured SIP system can be taken down entirely by a denial of service attack.
Telphi secures VoIP systems for businesses across the US, UK, and Canada. We assess, harden, and monitor your VoIP infrastructure against every category of threat. End-to-end call encryption, SIP authentication, toll fraud prevention, real-time anomaly monitoring, and full compliance configuration for HIPAA, PCI DSS, SOC 2, and GDPR. Our clients go from a VoIP setup with unknown security exposure to one that meets enterprise security standards and passes compliance audits.
Compliance certified across: HIPAA, PCI DSS Level 1, SOC 2 Type II, ISO 27001, and GDPR.
When a business moves from a traditional phone system to VoIP, they gain flexibility, cost savings, and features that a legacy system could never deliver. They also gain an attack surface that did not exist before.
A traditional phone line required someone to physically access a copper wire to intercept or abuse it. A VoIP system routes voice calls over the same internet connection your business uses for everything else. If that system is not secured correctly, it is accessible to automated scanning tools running on servers anywhere in the world, 24 hours a day.
The three most common VoIP security incidents Telphi encounters are toll fraud, eavesdropping, and service disruption. Toll fraud happens when an attacker gains access to a poorly secured SIP account and uses it to place large volumes of expensive international calls before anyone notices the bill. Losses of five figures in a single weekend are not unusual. Eavesdropping targets unencrypted voice traffic on the network. Service disruption through denial of service attacks floods the VoIP system with traffic until it stops processing legitimate calls.
Every one of these attacks is preventable with correct configuration. None of them require sophisticated attackers. They happen because most VoIP systems get set up for functionality first and security as an afterthought.
Telphi approaches VoIP security from the other direction. We assess the security posture of your VoIP infrastructure before anything else, identify every gap, and fix them systematically. For businesses in regulated industries, we then build the compliance framework on top of a foundation that is already properly secured.
A complete VoIP security deployment covers every layer from the network through to the application and the compliance framework. Here is what Telphi addresses in every engagement.
Every call on your VoIP system gets encrypted using SRTP for the voice data and TLS for the signalling layer. SRTP encrypts the actual audio content so that even if someone captures the network traffic they cannot listen to the conversation. TLS encrypts the call setup and control information so the details of who is calling whom and when cannot be intercepted. Telphi implements both encryption layers as standard on every deployment.
SIP is the protocol that most VoIP systems use to set up and manage calls. A misconfigured SIP setup is the primary entry point for the vast majority of VoIP attacks. Telphi hardens your SIP configuration by implementing strong authentication on every account, disabling anonymous access, restricting which IP addresses can register to the system, configuring fail2ban rules that automatically block brute force attempts, and removing default credentials that attackers routinely scan for.
Toll fraud prevention is built into every VoIP security deployment Telphi completes. We implement rate limiting on outbound calls, configure geographic restrictions that block call attempts to high-risk destinations, and set up real-time anomaly monitoring that triggers an immediate alert when call patterns deviate from normal usage. For businesses that have experienced toll fraud before, we conduct a full audit of how the breach occurred and close every gap.
Your VoIP traffic needs specific firewall rules that most generic IT configurations do not include. Telphi configures firewall rules specific to VoIP protocols, sets up a Session Border Controller where appropriate, implements network segmentation to separate voice traffic from data traffic, and configures quality of service rules that prioritise voice packets.
Telphi sets up real-time monitoring across your VoIP infrastructure that watches for attack signatures, unusual call patterns, authentication failures, and configuration changes that could indicate compromise. Alerts go to the right people immediately so incidents get responded to in minutes rather than discovered days later.
Before any hardening work begins, Telphi conducts a full vulnerability assessment of your VoIP infrastructure. We scan for open SIP ports, test authentication strength, check for known vulnerabilities in your VoIP software versions, review your firewall rules, and assess your network architecture for weaknesses. The assessment produces a written report with every finding ranked by severity and a clear remediation plan.
For regulated industries, Telphi configures the compliance layer on top of the security foundation. HIPAA requirements for healthcare voice communications. PCI DSS requirements for calls handling card payments. GDPR requirements for businesses with UK and European customers. SOC 2 controls for technology businesses undergoing audits.
Every VoIP security engagement follows a structured process. We assess before we fix and we document everything.
We start with a complete audit of your current VoIP infrastructure. We scan for open ports and exposed services, test authentication on all SIP accounts, review your firewall and network configuration, check encryption settings on your call traffic, and assess your compliance posture. At the end you receive a written security assessment report with every finding ranked by severity and a specific remediation recommendation.
Great for:
IT managers and CTOs who need to understand their current VoIP security exposure before presenting a remediation plan or preparing for a compliance audit.
We fix every finding from the assessment in order of severity. Encryption implementation, SIP hardening, firewall rule configuration, Session Border Controller setup, toll fraud prevention rules, geographic restrictions, and monitoring setup. Every change is documented.
Great for:
Businesses that have completed an assessment and need the remediation work executed correctly and completely.
For regulated industries, we implement the compliance configuration on top of the hardened security foundation. Call recording compliance, access control policies, audit trail configuration, data retention settings, Business Associate Agreements for healthcare, and documentation of security controls for audit purposes.
Great for:
Healthcare, financial services, and legal businesses that need their VoIP system to pass a compliance audit.
After the initial hardening and compliance work, we provide ongoing security monitoring, regular vulnerability scanning, compliance monitoring updates as regulations change, and an annual security review.
Great for:
Businesses that want continuous assurance that their VoIP security posture remains strong rather than a one-time fix that drifts over time.
The most financially damaging VoIP security incident most businesses experience. Attackers compromise a SIP account and use it to make hundreds or thousands of international calls in a short window. Bills of ten thousand dollars or more in a single weekend are not uncommon. The attack typically happens outside business hours when nobody is monitoring. Telphi prevents it through strong authentication, rate limiting, geographic restrictions, and real-time alerting.
Unencrypted VoIP traffic can be captured on any network segment between the caller and the called party and replayed later. For businesses where confidentiality of conversations matters, whether that is legal client discussions, financial conversations, healthcare patient calls, or executive communications, unencrypted voice is a serious liability. SRTP encryption makes captured traffic useless to an attacker.
A denial of service attack floods your VoIP system with traffic until it can no longer process legitimate calls. For businesses that depend on their phones for customer service, sales, or operational communication, even a short outage is costly. Telphi implements rate limiting, traffic filtering, and Session Border Controller protection that absorbs attack traffic without affecting legitimate call processing.
Automated tools continuously scan the internet for exposed SIP registration endpoints and attempt to authenticate using common username and password combinations. Telphi prevents this through strong authentication requirements, account lockout policies, IP restriction on SIP registration, and fail2ban rules that automatically block repeated failed authentication attempts.
Every industry has different VoIP security requirements. Telphi has implemented VoIP security and compliance configurations across all of the following sectors.
HIPAA compliant call encryption, PHI handling controls, Business Associate Agreements, audit trail configuration.
Learn morePCI DSS compliant call recording, SOX compliant call archiving, fraud detection monitoring, regulatory disclosure verification.
Learn moreAttorney-client privilege protection, encrypted call recording, access controls based on matter assignment.
Learn moreHigh-volume VoIP security, compliance monitoring across all call recordings, fraud detection at scale.
Learn moreSecure client communication on mobile and desktop VoIP, data protection compliance.
Learn moreFERPA compliant voice communications, secure parent and student communication systems, campus VoIP security.
Learn more"We had no idea how exposed our VoIP system was until Telphi showed us the assessment. The work they did transformed our compliance position and we passed our audit with no findings for the first time."
"After the toll fraud incident we needed to know our system was actually secure, not just assume it was. Telphi gave us that confidence and the monitoring means we would know immediately if anything unusual happened."
"Telphi understood immediately what our professional obligations required and built a VoIP security configuration that met them completely. The documentation they produced was exactly what our compliance review needed."
Every VoIP security deployment Telphi completes is built to meet the compliance standards relevant to your industry and your markets.
End-to-end encryption on all patient voice communications, access controls and audit logging, Business Associate Agreements, PHI handling procedures, and risk assessment documentation.
Automatic pause of call recording during card number entry, encrypted storage of all call recordings, access controls on recorded data, and regular penetration testing of the VoIP environment.
Security and availability controls across the VoIP infrastructure, annual third-party audit, continuous monitoring, and documented incident response procedures.
Data consent management for call recording notifications, right to erasure for call recordings, privacy by design in the VoIP architecture, and data processing agreements for UK and European operations.
Most businesses assume their VoIP system is secure because it was set up by an IT provider and it works. Working and secure are not the same thing. A VoIP system that routes calls correctly can still be completely open to toll fraud, eavesdropping, and compliance violations that would only become visible after an incident or an audit. Fill in the form below and a Telphi VoIP security specialist will reach out within one business day. No commitment required. Just a straight conversation about your current VoIP setup and what a proper security assessment would find.
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