--- title: Simplify troubleshooting with Network Logs url: "https://onomondo.com/blog/debugging-with-network-logs/" description: See network insights with Network Logs and debug IoT connectivity issues faster. They're handy for fixing issues with FPLMN lists, deactivated SIMs, and more. date_published: 2023-06-16 date_modified: 2026-03-10 content_type: Post site_name: Onomondo site_url: "https://onomondo.com/" --- # Simplify troubleshooting with Network Logs > See network insights with Network Logs and debug IoT connectivity issues faster. They're handy for fixing issues with FPLMN lists, deactivated SIMs, and more. ###### Debugging ###### 16.06.2023 # Simplify troubleshooting with Network Logs See insights about IoT devices with Network Logs and debug connectivity issues faster. Network Logs are handy for fixing issues with FPLMN lists, deactivated SIMs, and much more. ![michael bosson](https://cdn.growth.onomondo.com/app/uploads/2023/04/18102354/1516797037906.jpeg) ###### Michael Bosson Content Specialist at Onomondo [](https://www.linkedin.com/in/michaelbosson/ "See Michael Bosson Linkedin profile") ![cellular IoT network logs](https://cdn.growth.onomondo.com/app/uploads/2023/04/15103953/SIMs-Page-Network-Logs-e1760521291369-1024x559.png) When you connect devices to Onomondo’s cellular IoT network, you’re not only gaining global coverage, you also have a tonne of other benefits such as a powerful management platform, a public API, PAYG data pricing, and no-code cloud integration. Another area we really excel in is the ability to offer [deep network insights](https://onomondo.com/product/insight-tools/) for all devices no matter where they are in the world. This article explores our Network Logs insights tool and offers examples on it’s use when debugging IoT devices. ## Table of Contents ## What are Network Logs? Network Logs has helped hundreds of IoT business get quick and valuable insights on the connectivity status of their IoT and M2M devices. Network Logs show you which networks your devices authenticate with and attach to, including which technology was used. Most commonly you will see: - 2G (Also known as GPRS/Edge) - 3G (Also known as UMTS) - 4G (also known as LTE and currently also includes most LTE-M connections) - NB-IoT - LTE-M (separation of LTE-M from LTE signalling happened in later releases of the standards, and is still not common) In LTE, you will often also see two components of an attachment: - The network registration shown as `attached 4G connection`, which is the same as seeing `+CEREG: 5` when using the [AT Command AT+CEREG?](https://onomondo.com/blog/at-command-cereg/). - Data session creation shown as `attached data connection` and this is the same as activating the APN context. Seeing network insights in real-time and globally dramatically streamlines troubleshooting. We believe transparency is key, which is why Onomondo provides all information from the RAN to Core Network for your use. Watch our brief tech talk on Network Logs to find out more. *A brief Network Logs explainer.*## A GSM example The device will start attaching to our network by requesting permission. It is at this stage that the network list is checked, as well as other features like if there is an IMEI lock. This will appear as allowed or not allowed as well as the reason it was denied. For example, if the network is on your network list in Onomondo (aka network allow list or network whitelist), the device receives the response that it is allowed to attach. Conversely, if the network is not on your network list, then the connection will be denied. Additionally, if a device fails to authenticate with a network, Network Logs will show the reason for that. Here’s an example of a denied connection on GSM. ![](https://cdn.growth.onomondo.com/app/uploads/2023/06/28083105/network-denial.gif) *Network Logs showing not allowed to use GSM on a network.*## An attached data connection example This is when the device has successfully created a connection to the internet through Onomondo’s Core and can start sending data. This is also when a device is considered “online”. Depending on the technology, this step can have different names, such as “PDP context activation” in 2G/3G and “APN” or “Session activation” in LTE. ![](https://cdn.growth.onomondo.com/app/uploads/2023/08/28083213/dataattach.gif) *An example of an attached data connection in Network Logs.*For more information on any of the network logs, you can click on the row you are interested in. This information is also available via the [Onomondo API](https://docs.onomondo.com/) using a network-logs request. ![](https://cdn.growth.onomondo.com/app/uploads/2023/08/28083245/datadetails.gif) *Attached data details in Network Logs.*## Debugging using Network Logs Here’s a brief example of debugging a common cellular IoT problem using Network Logs. A forbidden networks list is part of the standards of telecom standards but can cause unwanted consequences. For example, if the device was turned on while the SIM was deactivated, no network logs are produced but can affect future performance of the device. ![A deactivated SIM event in Network Logs](https://cdn.growth.onomondo.com/app/uploads/2023/06/20073255/deactivated-sim-event.webp) *A deactivated SIM event in Network Logs.*Try activating the SIM again and testing again. If there are no issues you should see the device establish a connection next time it tries to connect to our network. ![A reactivated SIM event in Network Logs.](https://cdn.growth.onomondo.com/app/uploads/2023/06/20073431/reactivated-sim-event.webp) *A reactivated SIM event in Network Logs.*If you still don’t see any new network logs even though the device has tried to connect again, the device may have written all networks into the Forbidden network (FPLMN) list and [will need to be cleared](https://onomondo.com/blog/how-to-clear-the-fplmn-list-on-a-sim/). Networks are added to FPLMN list when they are not on the network list. This is to save time and energy by preventing the device to constantly try and attempt a network that has already been denied. However, if the network list is changed to include the network, it still may not connect to the network, if it was previously been denied. ![Network List changed event in Network Logs.](https://cdn.growth.onomondo.com/app/uploads/2023/06/20073549/network-list-changed.webp) *Network List changed event in Network Logs.*And that’s it. we hope this brief example shows you the value of Network Logs and how they can shorten the time you debugging your cellular IoT devices. ### Build your own network Enhance signal quality and network control with non-steered SIM cards. Connect all your devices securely to a global network with Onomondo. [ See our Global IoT SIMs ](https://onomondo.com/product/global-iot-sim/) ### Start testing Onomondo for free Ready to experience next-generation IoT connectivity? Create an account, explore the platform, and start testing Onomondo’s IoT SIM cards for free. [ Get started ](https://onomondo.com/pricing/) ## Related articles Read more about the topic ![Remote SIM Provisioning for IoT](https://cdn.growth.onomondo.com/app/uploads/2026/04/21115413/Remote-SIM-Provisioning-featured-1024x536.png) Articles###### Remote SIM Provisioning: What is it and how it works for IoT Connectivity Basics IoT SIM Learn what Remote SIM Provisioning is, how it works, and why it matters for IoT deployments – from eUICC fundamentals to SGP.32, form factors, and real-world benefits. [ Read more ](https://onomondo.com/blog/remote-sim-provisioning-iot/) ![iSIM](https://cdn.growth.onomondo.com/app/uploads/2026/03/01092112/iSIM-1024x536.png) Articles###### What is an IoT iSIM? How it works, benefits, and why it matters IoT / M2M SIMs If you’re building IoT devices today, you’re likely looking at traditional, physical SIM form factors, and possibly embedded SIMs. But there’s a newer form factor starting to reshape how connectivity is designed: iSIMs. So what actually changes with iSIMs—and when do they make sense to use? We break it down in this article. [ Read more ](https://onomondo.com/blog/what-is-an-iot-isim/) ![SGP.32 eSIM IoT interview with Henrik Aagaard](https://cdn.growth.onomondo.com/app/uploads/2026/03/31085742/eSIM-IoT-Henriks-interview-1024x576.png) Articles###### “eSIM IoT isn’t connectivity – it’s a device capability”. An interview about SGP.32 with Henrik Aagaard Future-proofing IoT IoT SIM You’ve probably heard a lot about eSIM IoT, SGP.32 – how much of it is substance and how much is noise? Henrik Aagaard separates the wheat from the chaff. [ Read more ](https://onomondo.com/blog/esim-iot-isnt-connectivity-its-a-device-capability-an-interview-about-sgp-32-with-henrik-aagaard/) --- *This is a machine-readable version of [Simplify troubleshooting with Network Logs](https://onomondo.com/blog/debugging-with-network-logs/).* *Last updated: March 10, 2026* ## About Onomondo Onomondo is a global cellular IoT connectivity platform providing IoT SIM cards, eSIM, and SoftSIM with a management platform, real-time diagnostics, and cloud integrations. Operates across 680+ networks in 180+ countries. Founded 2012, headquartered in Copenhagen, Denmark. ISO 27001:2022 certified. - Website: https://onomondo.com - Documentation: https://docs.onomondo.com - Knowledge Base: https://help.onomondo.com