... economical call system Display 1 call number and the key values Compatible with 1-key,2-key,3-key ... Guest call system Our MMC-2611P host is the most ... much on the cost. How the guest call system works?When guest needs services, just press the ... 315.6MHZ,433.5MHZWorking voltage: AC100-240V,DC 12VThis system mainly used in the office for calling the cleaner, ...