# How can I fix router problems? If things go wrong, it is often your own **router** that is to blame. Calling over the Internet works without problems in most cases. However, router problems can usually be fixed with little effort. This document is intended to give you **help** on how to **solve typical problems** . The errors listed below can usually be fixed by simply adjusting the **Configuration** in the router: * The call can only be heard in **one direction** . * Your VoIP device **does not register** or loses the registration again after some time. * The other party’s phone keeps ringing even though you have already **hung up** have. * You are **not reachable**. * from the outside. You can dial a number, but hear **no ringing tone**. * The **Call acceptance** is not transmitted **to the caller**. * The call **drops** after some time **from**. Various of the above errors do not necessarily occur immediately, but can appear with a delay. This can be reproduced especially in networks with several routers and/or several VoIP/SIP telephones. **What exactly does a NAT router do?** A router is used when there is only one Internet connection, but it is to be made available for several devices or computers on the local network. The NAT router therefore serves as a **distributor for one Internet connection** which establishes the Internet connection to your Internet provider independently. In doing so, it receives a globally unique IP address (in the format 123.123.123.123) from the Internet provider so that it can send requested data back to the router individually. The router in turn provides the Internet connection to all devices connected to it in the **local network (LAN)** . So that each VoIP device connected to the router can also be addressed individually, each of these devices automatically receives an **internal IP address** from the router. **What data is transmitted?** Your router must know that sipgate sends and receives both voice data and data for establishing the connection. These two types of information always reach your router via the same route: * Voice data is transmitted via UDP through the so-called RTP port. * Signaling data is transmitted via UDP through the SIP port. Both the RTP port and the SIP port can usually be defined in the **device settings** .\ For more information on exactly where you can set the SIP or RTP port, please refer to the manufacturer’s manual supplied with the device. **Where should the data go?** The router must know which device this data needs to be sent to. To do this, you need to know the local IP address of your VoIP device (e.g. 192.168.1.12). * Some devices have a **display**on which the IP address can be shown (for more information about the IP address status, please refer to the manufacturer’s manual). * **Softphones** (e.g. Phonerlite) always use the IP address of the computer on which they are used. * Your router can also help: in the **configuration interface** of the router, you can often find a corresponding list of the currently assigned local IP addresses on a status page. If you have determined the IP address, make a note of it for the next step. **Switching to TCP, TLS and or IPv6** In some cases, it can be helpful to change the phone’s SIP communication to TCP or TLS. Switching to IPv6 can also be helpful. Please refer to the following articles for all necessary information: [*How do I configure signal encryption via TLS?*](https://help.sipgate.de/hc/de/articles/4773527832081-Wie-konfiguriere-ich-die-Signalverschl%C3%BCsselung-via-TLS)[*How do I configure my VoIP phone with sipgate?*](https://help.sipgate.de/hc/de/articles/4402620523665-Wie-konfiguriere-ich-mein-VoIP-Telefon-mit-sipgate)[*What are the IP and port ranges of sipgate?*](https://help.sipgate.de/hc/de/articles/4983838712477-Was-sind-die-IP-und-Port-Bereiche-von-sipgate) **Example configuration of VoIP devices** Many VoIP devices use a **STUN server**to establish a connection to our server even when using a router with firewall/NAT. Unfortunately, this does not work properly with every router model. To work around the problem, please delete the STUN entry. Where you can disable the STUN server on your phone can be found in our [configuration help](https://help.sipgate.de/hc/de/articles/4402636353041-Konfigurationsanleitungen-So-verbinden-Sie-Telefone-mit-Ihrem-Account). If your router also offers the **SIP ALG** service, please disable it. If you use several VoIP devices in one network, you will find various tips in our configuration guides on how to set them up individually. **The problems are not gone?** Check the **current software** (**firmware**of the router. Most router manufacturers are constantly updating the firmware of their devices. You can usually download it **free of charge** from the manufacturer’s website. In the manufacturer’s manual you will find instructions for updating the firmware. If necessary, the **port forwarding** must be set up again after the firmware update. Alternatively, check the FAQ instructions on the manufacturer’s website or contact the manufacturer’s support. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://help.sipgate.de/cloud-telefonanlage/en/using-sipgate/allgemeine-losungen-beim-telefonieren-mit-sipgate/wie-kann-ich-probleme-mit-dem-router-beheben.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.