How to fix VoIP phone calls dropping or cutting out during conversations

Intermittent VoIP call drops, one-way audio, or calls that cut out mid-conversation are frustrating for any business. These issues are almost always caused by network conditions rather than the phone hardware itself. This guide walks you through a systematic approach to identify and resolve the most common causes of unstable VoIP calls on your 220 Internet Services connection.

Quick Fix Steps

If you need to get back on the phone quickly, try these steps in order. Each takes less than two minutes.

1. Restart your VoIP hardware. Power cycle your VoIP phone, ATA adapter, or router. Unplug the power cable, wait 30 seconds, then plug it back in.
2. Test with a different handset or softphone. If you have a second VoIP phone or the 220 softphone app, make a test call to isolate whether the issue is with a single device.
3. Move closer to your Wi-Fi router if you are using a cordless VoIP phone or a softphone on a laptop. Poor Wi-Fi signal is a leading cause of dropped calls.
4. Check for large downloads or uploads on your network. Pause any cloud backups, file syncs, or streaming services and test again.

Detailed Instructions

1. Identify the scope of the problem

Understanding whether the issue affects all calls or only specific scenarios will narrow down the cause significantly.

• All calls drop or cut out: The problem is likely with your internet connection, router, or the 220 VoIP service configuration.
• Only calls to certain numbers drop: The issue may be with the destination carrier or a specific call route. Note the numbers affected and include them in a support ticket if needed.
• Only calls from one handset drop: The problem is likely with that specific device, its cabling, or its network connection.
• Only calls at certain times of day drop: This points to network congestion or scheduled bandwidth usage on your connection.

2. Check your internet connection quality

VoIP calls require a stable, low-latency internet connection. Even if your internet "works" for browsing, it may not be stable enough for voice traffic.

1. Open a web browser on a computer connected to the same network as your VoIP phones.
2. Run a VoIP quality test. We recommend using a tool such as pingplotter.com or the free speed.cloudflare.com test.
3. Look at three key metrics:
   • Latency (ping): Should be under 100ms to Australian servers. Ideally under 30ms.
   • Jitter: Should be under 30ms. Jitter is the variation in latency and is a major cause of choppy or dropped VoIP calls.
   • Packet loss: Should be 0%. Any packet loss above 1% will cause noticeable audio issues.
4. If any of these metrics are outside the acceptable range, continue to the next section on network configuration.

3. Configure your router for VoIP traffic

Most consumer and small business routers need specific settings adjusted to handle VoIP traffic reliably. The two most important settings are SIP ALG and QoS.

Disable SIP ALG

SIP ALG (Application Layer Gateway) is a router feature that attempts to help VoIP traffic but frequently causes dropped calls, one-way audio, and registration failures. It should be disabled on almost all modern VoIP setups.

1. Log in to your router's administration page. This is typically done by entering 192.168.1.1 or 192.168.0.1 in your web browser.
2. Look for a section called NAT, Firewall, ALG, or Advanced Settings.
3. Find the option labelled SIP ALG, SIP Helper, or SIP Transformations.
4. Disable or untick this option.
5. Save your settings and reboot the router.

Enable Quality of Service (QoS)

QoS prioritises VoIP traffic over other network activity such as streaming or file downloads. Without QoS, a large download can starve your phone calls of bandwidth and cause drops.

1. In your router's admin page, look for a section called QoS, Traffic Management, or Bandwidth Control.
2. Enable QoS if it is not already active.
3. Set the priority for your VoIP devices to Highest or Premium. You may need to identify devices by their MAC address or IP address.
4. If your router supports it, enable WMM (Wi-Fi Multimedia) for wireless VoIP phones.
5. Save and reboot the router.

4. Check for double NAT

Double NAT occurs when two routers are connected in series — for example, a modem/router from your ISP with another router plugged into it. This configuration frequently causes VoIP call drops and registration failures.

1. Check if you have two devices performing routing. Common signs include:
   • Your VoIP phone is connected to a different network segment than your computer.
   • You have a modem/router combo from your ISP and a separate Wi-Fi router.
2. If you have two routers, you have two options:
   • Bridge mode: Put the ISP modem/router into bridge mode so it acts as a modem only. Your second router then handles all routing. Contact your ISP for bridge mode instructions.
   • Remove the second router: Connect all devices, including VoIP phones, directly to the ISP modem/router.

5. Check your VoIP phone's registration settings

Incorrect registration timers or codec settings on your VoIP handset can cause calls to drop after a specific duration, such as every 15 or 30 minutes.

1. Access your VoIP phone's web interface. You can find the phone's IP address by pressing the Menu or Settings button on the handset and navigating to Network or Status.
2. Log in with the phone's admin credentials. If you do not know these, check the label on the underside of the phone or contact 220 support.
3. Navigate to the SIP Account or Line settings.
4. Check the following values:
   • Registration Expiry: Should be set to 3600 seconds (1 hour) or lower. If set to a very high value, the phone may lose registration without realising it.
   • SIP Session Timer: If enabled, set it to 1800 seconds with a minimum of 90 seconds.
   • Codec priority: Set G.711a (PCMA) as the first codec. This is the most compatible codec for Australian VoIP services.
5. Save and reboot the phone.

6. Test with a wired connection

If you are using Wi-Fi for your VoIP phones, switch to a wired Ethernet connection temporarily to rule out wireless interference.

1. Connect your VoIP phone directly to your router using an Ethernet cable.
2. Make several test calls to confirm whether the issue persists.
3. If the problem disappears on a wired connection, your Wi-Fi network is the likely cause. Consider moving your router, changing the Wi-Fi channel, or adding a Wi-Fi access point closer to your phone.
4. If the problem continues on a wired connection, the issue is likely with your internet connection, router configuration, or the VoIP service itself. Contact 220 support with your test results.

If you have completed all the steps above and are still experiencing dropped calls, contact 220 support with the following information ready: the time and date of recent dropped calls, the numbers affected, your router model, and the results of your VoIP quality test.