--- title: "Calls drop or cut out mid-call" url: "https://enfonica.com/help/call-troubleshooting/calls-dropping" summary: "Every dropped call ends with a BYE, and the call's SIP trace in the Enfonica Console shows which side sent it. If calls drop at the same point every time, such as 30 seconds after the answer or about 15 minutes in, the time points to a specific cause. If calls drop at random, look at the side that sent the BYE." type: troubleshooting audience: everyone products: ["Cloud SIP", "Phone Numbers"] works_with: ["Any SIP PBX or SBC"] who_can_do_this: "Whoever manages your PBX and your Enfonica project" --- # Calls drop or cut out mid-call **Short answer:** Every dropped call ends with a BYE, and the call's SIP trace in the Enfonica Console shows which side sent it. If calls drop at the same point every time, such as 30 seconds after the answer or about 15 minutes in, the time points to a specific cause. If calls drop at random, look at the side that sent the BYE. **Applies to:** Cloud SIP, Phone Numbers **Works with:** Any SIP PBX or SBC **Who can do this:** Whoever manages your PBX and your Enfonica project First check the [Enfonica status page](https://enfonica.status.io/) for a known incident. ## Calls drop at the same point every time Note how long the dropped calls lasted, and then match the time to one of the following causes. A fixed time points to a timer, and each timer has a known cause, so this is the quickest kind of drop to trace. For the exact time, look at the call's **Duration** and **Timeline** in **Cloud Voice > Calls**. ### About 30 seconds after the call is answered When a call is answered, the answering side sends `200 OK`. The other side confirms it with an `ACK`. If the `ACK` never arrives, the answering side keeps resending `200 OK` and ends the call after about 30 seconds. **To check**, open the call's [SIP trace](https://enfonica.com/help/call-troubleshooting/find-call-sip-trace). This is the cause if the same `200 OK` appears again and again with no `ACK` in reply, and a `BYE` follows about 30 seconds after the answer. **To fix it**, allow both of Enfonica's signaling addresses, `34.87.239.197` and `34.87.254.143`, in both directions, in the firewall in front of your PBX (phone system). Then turn off SIP ALG on your router. SIP ALG is a router feature that rewrites SIP messages as they pass, and it can damage them. ### About 15 minutes in, on calls through your PBX Some PBXs refresh each call at a set interval, such as every 15 minutes, by sending a second `INVITE` (a re-INVITE). If the PBX then sends a malformed `ACK`, Enfonica can't route it and ends the call about 30 seconds later. For example, the `ACK` might be addressed to a different place than Enfonica asked for. **To check**, look at when the calls drop. This is the cause if they drop at about 15 minutes and 30 seconds. In the SIP trace, your PBX sends an `INVITE` about 15 minutes into the call, repeated messages follow, and then the call ends. **To fix it**, change your PBX or the network in front of it. Turn off SIP ALG on your router. Then look in your PBX's trunk settings for session timer or re-INVITE options to change. Your PBX vendor can confirm which setting applies. A packet capture from the PBX during a 16-minute test call gives them what they need. ### Exactly 4 hours Every call through Enfonica can last up to 4 hours from when it starts, including the time it rings. Then the call ends. **To check**, look at the call's **Timeline**. This is the cause if **Ended** is exactly 4 hours after **Started**. The **Duration** is a little less, because it counts from the answer. Nothing is wrong. For a call that needs to last longer, such as an open line between two sites, set it up to redial when the call ends. ## Calls drop at random times A random drop always ends with a `BYE` from one side of the call. Look at the side that sent it. To find the `BYE`, open the call's SIP trace, as described in [How do I see who ended the call?](https://enfonica.com/help/call-troubleshooting/calls-dropping#who-ended-the-call) ### Your PBX, dialer, or contact center platform ended the call **To check**, find the `BYE` in the trace. This is the cause if it goes from your system toward Enfonica. Select the `BYE` to see its `Reason` header, if it has one. The header often names the cause. For example, `Reason: SIP;cause=480;text="WebRTC disconnect (iceIdleDetection)"` from Genesys Cloud means that the agent's browser or device lost its connection to the platform. **To fix it**, check your system's logs for the time of the drop, or send the `Reason` to your platform's support team. If the drops follow one agent or one site, the cause is usually that person's device or internet connection. ### The other person, or their network, ended the call **To check**, find the `BYE` in the trace. This is the cause if it goes from Enfonica toward your system. Enfonica passes on the hang-up it receives from the phone network, so the call ended on the other person's side or in their network. **To fix it**, look at how often it happens. If it's one call, the other person most likely hung up or lost signal. If drops keep happening with the same number or network, send us two or three recent examples, and we'll check them with the carrier. ## Calls stay connected after the other person hangs up The other person has hung up, but your phone, PBX, or dialer still shows the call. The SIP trace shows whether Enfonica told your system that the call ended. ### Your system received the hang-up but didn't act on it **To check**, open the SIP trace. This is the cause if Enfonica sends a `BYE` and your system replies `200 OK`, which means that your system received it. **To fix it**, look between your PBX or dialer and the agent's phone. Check your system's logs for that call. Also check the router between them. A router that runs short of connection memory (its NAT table) can lose messages inside your network. ### The hang-up didn't reach your system **To check**, open the SIP trace. This is the cause if Enfonica sends a `BYE` several times with no `200 OK` in reply. Your firewall is likely dropping messages from one of Enfonica's signaling addresses. **To fix it**, allow both `34.87.239.197` and `34.87.254.143` through your firewall, in both directions. If the trace shows no `BYE` from Enfonica at all, send us the call, and we'll look at it. ## How do I see who ended the call? The side that sent the `BYE` ended the call. To find the `BYE` in the call's SIP trace: 1. In **Cloud Voice > Calls**, find the call and open it. 2. Under **SIP Insights**, select **View SIP trace**. The trace draws the call as a ladder of messages between columns, one column per system. 3. Find the `BYE` near the bottom. Its arrow starts at the side that ended the call. 4. Select the `BYE` to see the full message, including any `Reason` header. Enfonica's column is labeled with one of its signaling addresses, `34.87.239.197` or `34.87.254.143`. The other column is your PBX, dialer, or platform. To learn more about reading a trace, see [Find a call and read its SIP trace](https://enfonica.com/help/call-troubleshooting/find-call-sip-trace). ## What to send us Include these and we can find the call straight away. - The number that made the call and the number it called, in full international format (for example +61255501234). - The date and time of the call, with your timezone. - Whether the call was inbound or outbound. - The call ID, if the Console shows the call. - What happened: an error message, silence, a busy tone or a dropped call. [Contact support](https://enfonica.com/contact-support?article=%2Fhelp%2Fcall-troubleshooting%2Fcalls-dropping&topic=call-fault) ## Related - [Find a call and read its SIP trace](https://enfonica.com/help/call-troubleshooting/find-call-sip-trace.md) - [Calls connect but there's no audio, or audio only one way](https://enfonica.com/help/call-troubleshooting/one-way-or-no-audio.md) - [Poor call quality, or keypresses not recognized](https://enfonica.com/help/call-troubleshooting/poor-call-quality.md) - [Outbound calls aren't going through](https://enfonica.com/help/call-troubleshooting/outbound-calls-fail.md) - [Teams Direct Routing calls fail or don't ring](https://enfonica.com/help/teams-direct-routing/teams-calls-not-working.md) --- Web version: https://enfonica.com/help/call-troubleshooting/calls-dropping