VoIP and ghost call drops: Is it the ISP or your internal QoS?

Voice over Internet Protocol (VoIP) has transformed how businesses communicate: voice calls transmitted over broadband connections have replaced traditional telephone networks. For businesses, the benefits include lower international call bills, remote call management capabilities, CRM integration for easy access to customer details during calls, and AI-enabled call summaries and sentiment analysis.

While VoIP systems are generally reliable, disruptions like ghost call drops – when calls abruptly disconnect – remain a concern. We’ve all been there: a call to a bank or e-commerce customer care disconnects mid-conversation, sometimes followed by echoing silence, which is even more confusing and frustrating for customers.

For businesses, too many ghost call drops can lead to lost sales, customer attrition, and financial losses. In highly regulated sectors such as finance, insurance, and healthcare, frequent call drops create compliance gaps that can result in penalties.

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How critical is VoIP for businesses?

The expansion of 5G networks across the U.S. and the availability of instantaneous speeds and lower latency have made VoIP a viable enterprise solution. In 2025, North America generated $58 billion in revenue, accounting for 34.8% of the global VoIP services business, according to a market.us report.

Business users dominate the VoIP market, accounting for 78.7% of total adoption. The report also claims that businesses have saved up to 75% on telecommunication costs through VoIP. Furthermore, a VoIP HuntersOpens a new window report claims that CRM integration helps sales teams close deals 20% faster.

Most enterprise contact centers are now sophisticated VoIP-driven hubs capable of handling thousands of concurrent voice interactions with intelligent call routing and self-service speech solutions. According to ZoomOpens a new window , VoIP is great for remote and hybrid work models as it enables off-site and in-office teams to communicate seamlessly. The report claims that industries like IT, healthcare, finance, and retail have widely adopted VoIP.

What causes VoIP ghost call drops

Even with a perfectly reliable connection, issues like packet loss, jitter, and latency can occur along the path to your VoIP provider, especially during peak traffic. This can lead to ghost call drops and signal failures.

Some reasons for your ghost call drops could be:

• Insufficient bandwidth: VoIP call drops often stem from a combination of hardware and network-related issues. If your Internet connection is inconsistent or your other business applications are competing for bandwidth at the same time, your VoIP calls will be the first to suffer. You can address this by resetting the network device or by prioritizing VoIP calls in your router’s quality of service (QoS) settings. Your IT team can also use packet sniffers to identify applications and devices that are consuming excessive bandwidth.
• Talk off: Every number on your phone’s keypad plays a specific musical chord called dual-tone multi-frequency (DTMF); phone systems listen for this beeping sound to trigger a command. Ghost drops occur when the system mistakes your voice frequency for a command tone. This can be addressed by reducing your phone’s DTMF detection sensitivity.
• UDP timeouts: VoIP calls often use the user datagram protocol (UDP) for registration since the transmission control protocol (TCP) is too slow for voice. If a data packet is lost, TCP pauses your call and asks the server to resend it. UDP doesn’t stop if data is lost and moves to the next second of audio.
  UDP is designed to remain active throughout your call and during brief periods of inactivity. If your network device (router) is configured with a certain UDP session timeout, its firewall will end the session if there is silence (i.e., no data is sent) for longer than the UDP timeout. This can lead to call drops, especially for inbound calls from external or PSTN sources.  This can be fixed by changing the UDP session timeout settings on your network device.
• SIP timer issues: During calls, VoIP applications use the Session Initiation Protocol (SIP) to send periodic update messages to refresh sessions. These are crucial for maintaining call sessions. If the server fails to acknowledge the update message within the SIP timer window, the application assumes that your call has crashed and disconnects it. Unlike UDP timeouts, which occur at the network layer (level 3), SIP timer issues occur at the application layer (level 7) and involve the IoT device and VoIP provider. This can be addressed by adjusting the session refresh interval in your VoIP application.
• Interference from bad actors: Often called ‘drops,’ these are not caused by network issues but by threat actors. Attackers can use DDoS attacks to overwhelm VoIP servers, making it impossible for you to connect or continue calls.  They can also hijack sessions and intercept voice data packets to alter their flow, leading to deterioration in call quality or call drops.  Public VoIP endpoints are easy targets for such manipulation. You can address security-related issues through end-to-end encryption, firewall implementation, and traffic monitoring for anomalies.

Differentiating between ISP issues and internal hardware issues 

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To determine whether the issue lies with the ISP or the internal quality of service (QoS), your IT team can conduct a segmentation analysis. If call drops affect multiple users across your company, the issue is most likely at the ISP’s end. If the disruption is isolated to a specific user or area, or if the local area network (LAN) logs indicate brief physical disconnections, the fault lies with your internal hardware or network switch.

Some service providers also offer capabilities such as automatic call rerouting. If they detect a call interruption, the VoIP system immediately reroutes your call to a more stable network path.

The future is (still) VoIP

While data on the share of dropped VoIP calls and their financial impact is scarce, it doesn’t seem to be a frequent occurrence in regions like North America, where optical fiber and 5G FWA penetration is high.

VoIP is now integral to how most businesses communicate internally and with their customers. According to Precedence Research,  the U.S. VoIP marketOpens a new window is projected to reach $152 billion by 2034. Driven by growing cloud adoption and enterprise-wide AI mandates, VoIP offers businesses opportunities to deliver personalized, improved service. However, persistent call drops can disrupt many of the goals. Fortunately, many of the triggers behind call drops can be resolved with a simple setting change.