Automatic vs. Manual Network Selection–Which Is Best for Cellular Devices?

Ensuring reliable connectivity is critical for the smooth operation of IoT devices. Reliability depends on signal strength, which can be variable—good signal today might falter tomorrow. This raises a key question for IoT deployments: should your devices automatically connect to the strongest available network, or should you manage network selection manually?

In this article, we delve into the advantages and disadvantages of automatic versus manual network selection for IoT devices, how to make the most strategic decision, and how Zipit can provide the connectivity you need.

What is network selection?

Network selection is the process by which devices determine which cellular network to connect to when they are not within range of their home network. This decision is crucial for maintaining consistent connectivity and ensuring access to the best-quality signal available.

The main players in network selection are the device's SIM card and the Mobile Network Operator (MNO). The SIM holds the device’s identification, including network profiles and authentication keys. These profiles determine which networks the device can connect to.

There are two main types of SIMs: steering and non-steering. Steering SIMs actively guide the device towards preferred networks based on pre-defined criteria like cost or signal quality.  Non-steering SIMs permit the device to choose a network based on the strongest signal available.

SIMs must be able to store multiple MNO profiles for the flexibility and scalability needed for IoT devices. These SIMs include e-SIMs, multi-IMSI SIMs, or global roaming SIMs. Storing multiple MNO profiles allows for automatic or manual network selection.

Network selection goes beyond just the SIM card. Hardware compatibility also plays a crucial role. The device needs to have the necessary technical capabilities to connect to different carriers and use their various bands and frequencies. For example, a router certified for multiple carriers must support each carrier’s frequency bands for optimal network coverage. 

Automatic network selection 

Automatic network selection uses non-steered SIMs, which allow IoT devices to connect autonomously to cellular networks without manual intervention. Devices choose the most suitable network based on signal strength or predefined criteria. 

When a device powers on or begins to roam, it scans for available networks and selects the network with the strongest signal for better coverage and reliability. By continuously scanning and evaluating available networks, devices ensure optimal connectivity when roaming or in dynamic environments.

When initiating a connection, devices typically follow a predefined hierarchy of network preferences. This hierarchy typically prioritizes connecting to the home network first, followed by any operator-controlled preferences, and finally, random selection if no preferred networks are available.

Manual network selection

Manual network selection gives device managers control over network prioritization for IoT devices. Unlike automatic selection, it uses steered SIMs with a predefined list of preferred networks, prioritizing specific carriers based on contractual agreements or cost considerations.

The manual network selection process is straightforward. The device compares all available networks against your predefined list. It only connects to listed networks, strictly adhering to programmed priorities. Any fallback rules would dictate the next action if no preferred networks are available. Otherwise, the connection is dropped entirely.

Since signal strength is not the determining network selection factor, a device might maintain a connection to a weaker preferred network even when a stronger non-preferred option is available. This would hinder data transmission speed and reliability. 

What is PLMN?

A Public Land Mobile Network (PLMN) is a collection of networks established and maintained by an MNO. Each PLMN is identified by a unique ID number assigned by the MNO. These ID numbers vary based on the carrier, frequency bands, and geographical location.

In network selection, PLMN lists of predetermined networks are prepared in advance and stored on the SIM card. These lists serve as a reference for devices programmed for manual network selection, guiding them to prioritize specific networks based on contractual agreements or other considerations.

Without a predetermined list of preferred networks to guide its selection process, a device autonomously scans for available networks and selects the one with the strongest signal.

Forbidden networks

Every device has a Forbidden Public Land Mobile Network (FPLMN) list specifying networks that a device should not attempt to connect to. These entries are populated automatically based on past failed connection attempts or manually added by device managers to exclude unreliable networks.

The FPLMN list serves as a safeguard against undesirable network connections. However, there are instances where you need to override forbidden networks manually. For example, you might need to:

• Troubleshoot network issues: Manually overriding the FPLMN list can be a diagnostic tool to isolate network connectivity problems.
• Facilitate emergency connections: In critical situations, allowing connections to a previously blacklisted network could be necessary.
• Maintain optimal performance: Network conditions can change. Periodically reviewing the FPLMN list allows you to remove outdated entries and improve connectivity.

For reliable connectivity, you should regularly review and reset the FPLMN list. As network landscapes evolve, new networks emerge, and previously unreliable ones might improve. By keeping the FPLMN list updated, you ensure your device has the flexibility to adapt and connect to the best available network.

Should you choose automatic or manual network selection?

The choice between automatic and manual network selection significantly influences the connectivity and performance of IoT devices. 

Manual network selection has inherent limitations. Unlike automatic selection, which dynamically switches to networks with stronger signals, manual selection may persistently connect to a predefined network, even if a better alternative is available.

Sticking to a network with a weak signal in manual mode can result in data packet losses. This means that data transmitted by the device may not reach its intended destination, leading to communication errors, delays, or service disruptions. These packet losses can significantly affect operational efficiency and safety in critical IoT applications, such as remote monitoring or industrial automation.

Given IoT devices' widespread deployment and often remote nature, automatic network selection is preferred in most scenarios.

Learn more: Scaling IoT Globally: A Guide to Global SIM Strategies & Solutions

Advantages of choosing automatic network selection

Stronger signal strength

By prioritizing networks with the strongest signals, automatic selection ensures optimal coverage quality and minimizes the risk of data packet losses. This translates to reliable communication and uninterrupted data transmission, even in challenging environments.

Reduced management overhead

Automatic selection eliminates the need for manual configuration and ongoing network performance monitoring for each device. This is ideal for large-scale deployments where managing individual devices might be impractical.

Seamless connectivity

Devices can maintain consistent communication with minimal user intervention. Automatic selection continuously scans for available networks and adapts to changing signal conditions.

Versatility

The ability to dynamically choose networks based on signal strength provides greater versatility. This approach ensures optimal connectivity in diverse environments and deployment scenarios without requiring manual adjustments.

Reduced energy consumption

Devices with automatic network selection experience fewer disruptions and require less frequent reconnection attempts, leading to prolonged battery life and enhanced overall device longevity.

When manual network selection makes sense

While automatic network selection is generally preferred for its efficiency and simplicity, there are scenarios where manual selection may be more appropriate. 

Automatic selection excels in most situations, but manual selection offers a strategic advantage when your devices venture outside the home network. This becomes particularly relevant when roaming occurs within the coverage area of networks with agreements or partnerships with your home network provider.

In these scenarios, manual selection allows you to prioritize affiliated networks. This avoids disruptions that might occur when switching to entirely new providers. Additionally, agreements between network providers may offer preferential roaming rates or guaranteed service levels for specific network features. By prioritizing affiliated networks through manual selection, you can reduce connectivity costs and ensure your devices connect to networks that deliver the level of performance your applications require.

Network selection becomes more complex when your devices roam globally. For example, consider a SIM card from a Canadian carrier like Bell that primarily functions within Bell's network in Canada. The coverage plan for this SIM includes roaming, so the SIM can also leverage agreements with other networks like AT&T in the United States. Additionally, carriers negotiate rates for roaming, which fluctuate regularly and may influence the selection of carrier networks for roaming. These cost-related factors are also part of the calculus for how a SIM may choose which carrier networks to roam onto.

Zipit SIMS for optimal coverage worldwide

Ensuring reliable connectivity for your IoT devices worldwide can be a challenge. Zipit SIMs simplify this process. Zipit SIMs leverage multiple carrier relationships and global roaming capabilities to deliver seamless connectivity in diverse deployment environments.

Zipit offers a range of steering and non-steering SIM options designed to meet the unique connectivity requirements of IoT deployments. Zipit’s roaming SIMs allow for manual or automatic network selection, so devices can scan and connect to the most robust network signal available without defaulting to a predetermined carrier. 

In markets like the United States, where a Zipit SIM is primarily designed to work with a home network, devices can still assess network strength to ensure optimal connectivity. A Zipit SIM with AT&T as the "home network" in the US can also connect to over 700 MNO networks in 160 countries worldwide, providing unparalleled coverage and reliability. Likewise, Zipit has direct relationships with Tier-1 carriers like Telefonica, KPN, and Vodafone, which also provide global SIMs that Zipit can use to support global IoT deployments.

Contact Zipit to learn which of Zipit’s solutions can best help you simplify your IoT connectivity worldwide. 

You may also like: 

• IoT Device Management: How to Control Cellular IoT Devices Successfully
• Global IoT Connectivity: Understanding the Fundamentals
• Cellular IoT Explained: Is it Right for Your IoT Solution?