Grandstream HT881 Analog Gateway

The HT881 is the larger sibling of the HT841, with eight FXO ports instead of four. It suits sites with a full set of landlines: a medical centre, a car showroom, a government-facing office or a hotel that has accumulated numbers over the years and is now moving to an IP PBX or a hosted phone service. All eight lines become SIP trunks, and the one FXS port keeps an analogue fax, a lift phone or a door phone connected.

Its value is resilience. If the network or the PBX goes down, a failover SIP server can take over, and if the gateway itself loses power, the FXS port is relayed directly to an FXO line so that one analogue phone still works. Disconnects are detected by busy tone, polarity reversal or loop current, which avoids lines being held open.

The unit is only 190 x 100 x 28 mm and 460 g. It takes 802.3af PoE on one of its two gigabit ports, or a 12 V adapter bought separately, and can also act as a NAT router. Deployment at scale is simple with TR-069 or encrypted configuration files, and calls can be protected with TLS and SRTP.