Choosing the right ONU (Optical Network Unit, or "optical modem") for a household centers on matching the operator's network, meeting the home's service needs, balancing stability and expandability, and avoiding the issue of "buying a device that can't be used." There are three core prerequisites (determining if it will work):
Confirm the ISP's Access Protocol
Different ISPs use different PON network protocols. Protocol incompatibility = device rendered useless. You must consult customer service in advance (China Telecom 10000 / China Mobile 10086 / China Unicom 10010).
Mainstream protocols: GPON (most common, used by Telecom / Unicom / Mobile), EPON (used by some regional Mobile / cable operators), XGS-PON/10G-PON (for Gigabit+ broadband, future trend).
Note: For 100M/Gigabit broadband, GPON/EPON is sufficient. If planning to upgrade to multi-gigabit/Gigabit+ broadband, choose an XGS-PON model directly (which is backward compatible with Gigabit).
Confirm the Authentication Method
The ISP authenticates the ONU. Only authenticated devices can receive broadband configuration. Common methods:
LOID Authentication: Mainstream for Telecom/Unicom. Requires entering the LOID code provided by the ISP (can be found on the label of the old ONU).
SN Authentication: Mainstream for Mobile. The device's SN code is pre-registered in the ISP's system; it's plug-and-play.
Purchasing Advice: Prioritize ISP-customized models (Huawei, ZTE, FiberHome) for 100% compatibility. For self-purchased models, clearly inform the seller "supports XX ISP's XX authentication."
Confirm the Household Bandwidth Cap
The ONU's port speed determines if your broadband speed can be fully utilized, avoiding "a small horse pulling a big cart":
100M Broadband: Can choose 100M or Gigabit ports (Gigabit port is recommended for future upgrades).
Gigabit Broadband: Must choose Gigabit WAN/LAN ports (labeled "GE"), and the device must support "Gigabit rate forwarding."
Multi-gigabit/Gigabit+ Broadband (e.g., 2Gbps/10Gbps): Choose 2.5G/10G ports (labeled "2.5GE/10GE").
