The Siemens S30810-Q2901-X-9 SLMO is a Subscriber Line Module Cost Optimized Board. It offers 24 connections for the connection of optiset E- and optiPoint 500 devices.The SLMO is compatible with Siemens Hipath 3700 /3750 and 3550 systems and at least 1 is required for Optiset/optiPoint phone access.