You provision CPE for branches and require 'primary dies, backup takes over'. The vendor pushes dual-standby (+$28) saying single-standby is slow. How slow exactly? Let the numbers speak.
The two schemes switch differently
- Single-standby (DSS): only one SIM online; primary dies -> reconnect backup -> re-register, 20-60s, all TCP drops.
- Dual-standby (DSDS): both registered; primary dies -> switch data path to backup in seconds, 1-5s drop, TCP usually survives.
The business impact gap
- Single-standby 20-60s outage: POS timeout, stream black screen, VPN reconnect.
- Dual-standby 1-5s: face-pay retries once, stream stutters half a second.
Is the extra $28 worth it
- Transactions/streaming/telemedicine: 1 min down = lost money and customers, dual-standby pays.
- Dashboards/collection/low-speed IoT:几十秒 outage is invisible, single-standby suffices; save the cash for a better antenna.
Pick single or dual standby not from the spec sheet, but from what you lose in those 30 seconds.
FAQ
How to choose 4G CPE antennas and ports?
External high-gain antennas improve weak-signal areas; check LAN port count, PoE, SIM slot.
Single-SIM or dual-SIM (failover) CPE?
Dual-SIM standby auto-switches when the primary fails; most cases single-SIM suffices, dual for redundancy.
What is PoE on a 4G CPE for?
One cable carries data and power—no separate PSU; ideal for ceiling/outdoor installs.
Is the max-device count (client capacity) usually overstated?
Look at concurrent connections and real throughput, not the advertised max clients.