Public Questions & Answers

Typically two different carriers provide the strongest redundancy because you avoid a single network outage affecting both SIMs. If both SIMs sit on the same network, you still gain some resilience for plan management and failover behavior, but the geography and core network diversity is limited. If you can’t get two carriers, we can design a resilient setup using the same-network SIMs by configuring health checks, failover timing, and preferred SIMs, and …

Failover tests should mirror real outages and cover the services you depend on. Common pitfalls include assuming failover works just because a SIM registers or shows signal strength, not exercising actual traffic or critical applications, and not validating how long recovery takes or how VPN and remote access behave after the switch. Other frequent misses are testing at the wrong site conditions, skipping alert delivery checks, and not documenting the exac…

Plan a staged test that mirrors your site: verify both SIMs register, obtain their APNs, and pass traffic to the critical endpoints you use in production. Simulate failures: block the primary WAN, create a weak signal, or disable mobile data, and watch how the router switches paths. Confirm alerts are received and that active sessions, VPNs and remote access survive or recover cleanly after the switch. Document the configuration and test results: health ch…

Two different carriers usually provide the best redundancy because the whole point of dual SIM is to avoid a single carrier outage affecting your site. SIMs from the same network still have some value—for example, if one service has a different APN, billing arrangement, or priority, or simply for operational simplicity—but they do not offer the same geographic and network diversity as two different carriers. If you can't get two different carriers, you can…

Choose two carriers that provide real coverage diversity at your site. Look for networks with strong signal at the installation location and, ideally, different core networks. Consider practical differences that affect uptime: carrier plans, APN options, roaming rules, data caps, and how each SIM is billed. Also decide whether you want automatic failover or a manual switch, and ensure the router and management platform can enforce that policy. Plan a hands…

That depends on the router’s failover rules and on how failure is detected. Some systems swap because the mobile connection drops outright. Others watch whether traffic can still reach a known destination, which is often more useful because a link can stay technically connected while being practically unusable. The transition may be quick, but the real question is whether the application can tolerate a short interruption while the router re-registers and r…

Two different carriers usually provide the best redundancy, because the whole point of dual SIM is to reduce the chance that one carrier outage, congestion problem or coverage gap takes the site offline. Using two SIMs on the same network can still help with plan management or swap-over behaviour, but it does not give the same independence. Comset will normally ask which carriers work best on the site, whether the router is fixed or mobile, and how critic…

Two SIMs on the same carrier can protect against a damaged SIM, an account problem or a plan-specific issue, but they usually share much of the same tower and core network infrastructure. That means they provide less geographical and network diversity than SIMs from different carriers. Same-carrier dual SIM can still be useful where one service has a different APN, billing arrangement or priority, or where operational simplicity matters. For stronger redu…

Test both SIMs independently first. Confirm that each registers, receives the expected APN, passes traffic and can reach the services the site actually uses. Record signal-quality readings and data performance at the installed antenna position, not only on a workbench. Then simulate failures: block the health-check target, remove the primary WAN, disable mobile data, create a weak-signal condition if practical and verify the router changes paths within th…

No. Dual SIM gives the router two services to choose from, but reliable failover depends on how the router tests the active connection and when it is told to switch. A SIM can remain registered to a tower while internet access is unusable, so checking only registration or signal strength may not detect a real outage. The configuration should define health-check targets, failure thresholds, retry timing, preferred SIM, data limits and the conditions for re…