PSM and eDRX Explained: Power-Saving Network Features for IoT Devices

Battery life is a critical component for successful IoT deployments. Modern IoT deployments require lifetimes measured in years, not months. For devices that demand unattended operation, energy efficiency is mission-critical. Whether monitoring soil conditions for agricultural crops in remote fields, tracking a complex network of global shipments, or powering infrastructure sensors embedded throughout smart city technology, devices must remain functional, reliable, and low-maintenance over extended periods.

PSM (Power-Saving Mode) and eDRX (Extended Discontinuous Reception) are two 3GPP-standardized cellular features designed specifically to support battery-powered IoT devices at scale. These technologies have redefined what’s possible for low-power IoT applications by enabling devices to dramatically reduce energy consumption while maintaining connectivity in the field.

In this article, we’ll explore how these features work and the challenges many IoT OEMs face when looking to obtain global access to these technologies. We’ll explore how a partnership with an authorized MVNO like Zipit Wireless helps OEMs scale efficiently and profitably across diverse global markets.

PSM and eDRX: power-saving solutions for IoT devices

Power management is essential for the long-term viability of any battery-driven IoT application. Standardized in GPP Release 12 and 13, respectively, PSM and eDRX aimed to make the deployment of battery-operated IoT devices widely scalable and still cost-efficient by implementing energy conservation strategies that facilitate optimal device performance. The PSM and eDRX power-saving features can reduce battery consumption by 90% or more, dramatically changing how massive, international deployments in industries like agriculture, energy, logistics, utilities, and more scale their operations.

Addressing IoT deployment realities: dispersed, remote, and highly mobile

Designed specifically for devices that need to perform in the field for extended periods, PSM and eDRX’s battery-extending functionality reduces the need for human interaction and intervention. Many devices are positioned in remote, difficult-to-access, or far-flung locations. In these applications, manual intervention is costly, time-consuming, and creates additional administrative complications. These devices, like agricultural sensors, can be impractical to implement at scale without battery-saving features.

Other IoT devices are highly mobile, like asset trackers or logistics sensors. These may cross multiple international borders while in use, making frequent battery changes inconvenient. Battery-related device outages can result in crucial data loss, degraded performance, and customer frustration.

There’s also the simple cost of physical battery replacements. Devices that don’t rapidly drain batteries are cheaper to produce and ultimately more marketable to end-users. PSM/eDRX functionality creates a win for both manufacturers and the customers who depend on their products.

What is PSM for IoT devices?

PSM (Power-Saving Mode) is a cellular network feature that allows battery-powered IoT devices to conserve power and extend their overall service life by entering into a state of deep sleep.

PSM was an LPWAN (Low-Power Wide-Area Network) feature first introduced in 3GPP Release 12, which aimed to optimize power consumption for devices operating on LTE networks. This standard is implemented on cellular networks like NB-IoT, LTE-M, and LTE Cat 1 bis to dramatically reduce the power consumption between device transmissions. By entering into a state of deep hibernation, the battery life of a device is significantly extended. This creates time and cost savings, prolonged device lifecycles, fewer truck rolls and maintenance calls, and better device efficiency.

PSM was developed to encourage the mass adoption and proliferation of devices despite pre-existing limitations by improving battery efficiency within networks. When a device enters PSM, it shuts down most of its radio functions, while remaining registered with the network rather than completely disconnecting. In the absence of a feature like PSM, devices must routinely awaken to maintain network connectivity by responding to “pages” that verify their presence.

Key functionality traits of PSM:

Deep sleep state

When a device enters Power-Saving Mode, its cellular modem powers down almost all of its radio and signaling functions, dramatically reducing energy consumption. However, unlike airplane mode or full shutdown, the device remains logically registered with the cellular network. This means that the network “remembers” the device and can seamlessly reestablish communication once it wakes up. The device does not need to renegotiate its identity or settings with the network, allowing it to resume operation quickly and efficiently. This “deep sleep with awareness” design is especially important for unattended devices deployed in the field.

No need to reattach to the network

In traditional mobile device behavior, waking from a low-power state typically requires a full reattachment and reauthentication with the network, a process that consumes both time and energy. With PSM, the IoT device can skip that step. When it exits sleep mode (either on a scheduled interval or when it needs to transmit data), it can immediately begin sending data without the overhead of reestablishing its network session.

This streamlined process results in:

• Significant energy savings over the lifetime of the device.
• Reduced airtime costs, especially on usage-based plans.
• Faster data transmission cycles, which can be critical for event-based or time-sensitive IoT applications.

Unreachable by networks

During its sleep period, IoT devices in PSM cannot receive any incoming messages from the network. It is invisible to the network while sleeping, meaning:

• It cannot receive downlink commands, such as firmware updates or control signals.
• It cannot receive SMS or data pages.
• It will not respond to incoming calls or ping attempts.

This is acceptable, and even ideal, for many use cases where the device only needs to send data periodically, not maintain real-time two-way communication. Applications like water meters, parking sensors, or agricultural telemetry systems prioritize battery longevity over always-on connectivity. For scenarios that require occasional downlink communication without constant wakefulness, eDRX (extended Discontinuous Reception) is often used in conjunction or as an alternative.

How does PSM work? A step-by-step guide:

1. The device attaches to the network

• The IoT device initiates a connection with the cellular network just like any other LTE device.
• During this process, it negotiates a PSM timer (specifically the T3412 Extended Timer) with the network. This timer defines how long the device can stay in PSM before checking in again.

2. The device transmits data

• The device sends its required data (e.g. sensor readings, location, event status).
• After the transmission is complete, the device stays briefly reachable in case the network wants to send downlink data. This window is called Active Time (T3324 timer).

3. The device enters PSM

• If no downlink data is pending, the device enters Power Saving Mode.
• In this mode:
• The modem powers down most radio and signaling functions.
• The device becomes unreachable by the network.
• The device remains logically registered, and it does not detach or release its identity.

4. The device stays asleep

• While in PSM, the device consumes minimal power, often just enough to run internal clocks and sensors.
• The network considers the device “attached,” but does not try to contact it.

5. The device wakes up

• The device wakes up when the T3412 timer expires (scheduled check-in) or when it has new data to send (event-based wake-up).
• It then resumes normal operation, transmits data if needed, and can re-enter PSM again.

What is eDRX?

eDRX is a cellular network power-saving feature that prolongs the battery life of IoT devices connected to LTE networks. eDRX is specifically tailored for IoT devices that need to stay reachable by the network but do not require real-time connectivity. This allows the device to sleep for longer intervals between listening for downlink messages from the network. This feature, released after PSM in GPP Rel. 13, strikes a balance between battery efficiency while still supporting two-way communication.

eDRX is more responsive than PSM and is best applied to devices that can tolerate some degree of moderate downlink latency. The device remains reachable, but its listening and response time is delayed to reduce its energy consumption and facilitate longer battery life. This differs from PSM, which becomes fully unreachable by networks during its sleep state.

eDRX offers a middle ground: the device saves power but wakes up occasionally to check for messages. PSM offers a deeper, longer sleep state, which is useful when the device only needs to report data periodically and doesn’t need to listen for incoming communication.

Key functionality traits of eDRX:

Intermittent sleep with downlink listening

When a device enters eDRX mode, it reduces power consumption by extending the time periods between when the modem listens for paging messages from the network. Unlike traditional DRX (Discontinuous Reception) cycles used in smartphones, eDRX allows IoT devices to “sleep” much longer, anywhere from several minutes to hours, without fully disconnecting from the network.

During this sleep period, the device powers down its modem but remains logically registered, and periodically wakes during a Paging Time Window (PTW) for incoming messages. The balance of sleep and limited listening is useful for devices that need long battery life but cannot become entirely unreachable.

No need to reestablish network sessions

Even though the device is asleep between paging windows, it does not need to reattach or reauthenticate with the network each time it wakes up. It maintains its network sessions across sleep cycles, allowing it to receive downlink messages efficiently when scheduled and transmit uplink data. This efficient power-state management enables

• Longer battery life for devices that do not need constant connectivity
• Lower communication overhead for sporadic transmissions
• Predictable and configurable wake/sleep behavior for time-sensitive tasks

Delayed network reachability

One of the main advantages of eDRX over Power Saving Mode is that the device is reachable during its paging windows, albeit on a delayed basis. While the device sleeps between cycles, it cannot receive messages, but once it enters its programmed PTW, the network can deliver downlink commands, alerts, or configuration updates. This delayed but scheduled network reachability enables:

• Support for firmware updates, control messages, or remote triggers
• Use in applications where real-time responsiveness isn’t required, but periodic listening is beneficial
• Compatibility with applications that occasionally receive messages but don’t always need to be on, like a smart meter or wearable device that needs to check for updates every few hours.

How does eDRX work? A step-by-step guide:

1. The device connects to the network

• When the device initially attaches to the network, it negotiates two key parameters:
• The eDRX cycle length: how often it checks for messages.
• The Paging Time Window (PTW): how long it listens each time it wakes.

2. The device transmits data

• The device sends its uplink data — telemetry, location, alerts, etc.
• After transmitting, the modem enters an eDRX sleep cycle.

3. The device sleeps

• During the eDRX cycle:
• The device powers down the modem to save battery.
• It is not listening for network messages outside of the PTW.
• The device stays logically registered, so it doesn’t need to reattach.

4. The Paging Time Window (PTW) begins

• At the start of each eDRX cycle, the device wakes briefly and listens for incoming pages from the network.
• If the network sends a message (e.g., a firmware update or control command), the device receives it and responds.

• If nothing is transmitted during the PTW, the modem powers back down and the device remains asleep until the next scheduled PTW.

eDRX vs. PSM: a comparison

eDRX and PSM are both 3GPP-defined power-saving features used in cellular IoT LPWANs like LTE-M and NB-IoT. While they share the common goal of extending battery life, they operate in fundamentally different ways and are designed to support different communication needs. Understanding when to and how to use each, or both, is key to optimizing performance, reliability, and energy efficiency across worldwide IoT deployments.

Furthermore, partnering with a trusted, authorized MVNO connectivity partner is essential. This collaboration ensures that your device fleets can continuously access these features, even as they travel across different networks and cross global borders.

Can a device combine PSM and eDRX?

Yes, a device can combine eDRX and PSM. In some IoT deployments, they are used together to maximize power efficiency while preserving some level of network reachability. For example, a GPS asset tracker might use eDRX to remain reachable every ten minutes during movement hours. The tracker may then enter PSM overnight or between scheduled location updates to maximize battery longevity.

Power-saving features and permanent roaming: a global challenge for IoT deployments

PSM and eDRX have become popular features on LPWAN networks worldwide, but accessing them can be difficult for unprepared IoT OEMs. NB-IoT and Cat-M1 were the first to adopt such technologies, though they’ve now expanded across LTE networks. However, access to low-power features on these networks is almost always restricted to local SIMs. In short, just because your device supports PSM and eDRX doesn’t mean the network will allow it.

Global carriers typically do not allow permanent roaming in low-power/power-saving modes. To access PSM and eDRX, IoT OEMs must acquire native connectivity SIMs for each device deployment region. Unless manufacturers can obtain specific network carve-outs, they are prohibited from leveraging features like PSM or eDRX while roaming worldwide, even if they have the firmware and software to support the technology.

Negotiating native connectivity with international carriers is a daunting undertaking for any device OEM, as each carrier poses its own set of rules, regulatory hurdles, and contractual stipulations. Multi-network and multi-country deployments require understanding which global cellular providers offer PSM/eDRX access and on what bands, and how to most affordably and effectively obtain native connectivity. Knowing the various limitations and restrictions of international carriers, and appropriately factoring this convoluted and intertwined information into deployment strategies is time-consuming and resource-intensive, and rarely the best use of the innovative minds behind IoT device launches.

Without a global perspective on roaming restrictions and intimate understandings of local network nuances, configuring these strategies is unlikely to be successful.

Access power-saving features on a global scale with Zipit Wireless

Zipit Wireless offers direct access to global network support for PSM and eDRX features across continents. With Zipit’s robust global contracts, IoT devices can natively connect to networks that honor power-saving mode negotiations, enabling consistent PSM/eDRX behavior and maximizing energy efficiency from the moment a device powers on. Zipit builds battery optimization on a global scale into the connectivity layer of your deployment strategy.

Extended battery life not only promotes better device efficiency and easily scalable deployments, the extended device lifecycle creates additional monetization opportunities. Zipit Wireless’s simplified billing management platform streamlines cellular data usage, automates billing cycles and subscription renewals, and maximizes recurring revenue potential for IoT OEMs.

Learn more: Can You Future-Proof Your IoT Strategy? A Roadmap for Long-Term Success

Engineer PSM/eDRX compatibility from the outset

PSM and eDRX logic must be incorporated into IoT devices from the initial design stages onward. From firmware to module software to network, PSM/eDRX compatibility must be built into every facet of the device’s design. If an OEM plans on leveraging these power-saving network features, it needs to factor these choices in from the outset of the project. In addition, IoT device OEMs must understand if and where their devices’ low-power needs will be supported and where native connectivity will be demanded.

Zipit partners with manufacturers from the beginning of the deployment process, offering industry-informed guidance on how to best utilize the power-saving features of IoT networks to extend battery life and improve device efficiency, and promote deployment scalability. If you have a global expansion roadmap in mind, we will help you procure optimal connectivity across networks and carriers.

Unlock exclusive relationships with global Tier-1 carriers

Unlock exclusive relationships with global Tier-1 carriers

Zipit offers true native connectivity that circumvents the limitations of permanent roaming. Through our robust network of exclusive Tier-1 agreements across key global markets, Zipit gives OEMs and IoT companies direct access to local networks, ensuring PSM/eDRX feature availability. Our carrier integration will respect your device’s power-saving negotiations during attach procedures, and our multi-network flexibility ensures that you don’t lose this agility as your mobile use cases travel. We aim to create battery-optimized connectivity that works consistently across borders, maximizing device performance.

Many of our MVNO competitors do not support Cat-M1/NB-IoT network connectivity, automatically excluding them from these power-saving opportunities. Through Wireless Logic, our parent company, we not only offer IoT-specific network strategies, but our carrier portfolio extends to over 50 international carriers, giving us truly global access.

Discover recurring monetization opportunities

Discover recurring monetization opportunities

Battery life is not merely a design feature for cellular IoT, it’s a revenue enabler. Devices that can operate for years without maintenance unlock new business models: subscription services, usage-based billing opportunities, and global “IoT-as-a-Service” offerings. But these models only work at scale when they can stay online, perform reliably, and remain power-efficient everywhere they’re deployed. If your connected device only lasts 6 month in the field, you’re selling a disposable product. If it can last 6+ years with Zipit-enabled PSM/eDRX support, you’re delivering a monetizable service.

Global access to PSM and eDRX is essential for IoT monetization, and Zipit’s native connectivity infrastructure builds that foundation. Beyond that, we help OEMs strategize industry-specific monetization strategies designed to maximize each deployment’s recurring revenue streams. We understand that IoT monetization is not a one-size-fits-all solution, and we leverage over a decade of experience to help each manufacturer craft revenue-generating models that best suit their specific needs. This stands in stark contrast to most carriers or MVNOs, who try and force outdated or ill-fitting monetization solutions onto highly complex and dynamic IoT applications.

Learn more: What is Telecom Billing and How to Choose Billing Software for IoT Devices

Zipit Wireless: uniting low-power with peak performance

With Zipit, your IoT devices can enter invaluable deep sleep modes without being kicked off networks and suffering performance outages, predictably perform across regions, and maintain power-efficient operations without costly workarounds or physical SIM swaps.

Contact us and learn more about how we can help OEMs strategize and deploy battery-powered, low-consumption devices on a global scale. Zipit Wireless makes global power-savings part of the plan from day one.

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