8001b is a 8-channel gsm fixed wireless terminal. It can produce a fxs line to allow a regular phone to be connected and used just like a local landline(pstn) except your calls will go out the gsm network. This device can both receive and make calls. The main application is: connecting the rj-11 fxs line to connect ordinary telephone set for voice call, to connect pbx for call extentions, to connect billing systems for public phone use, to connect voip gateway to realize voip call termination, to connect alarm system for security purpose, etc. It is not a voip gateway, nor a gsm+voip gateway, it is a gsm fixed wireless terminal that produces a analog fxs phone line. 1.It is a 8-channel gsm fixed wireless terminal that has 8 ports fxs interfaces; 2.Each port has 1 sim card (1.8v, 3v) 3.It can connect with ordinary telephone set, pbx, voip gateway, billing meter etc. 4.It is compatible with asterisk 5.Dialing tone frequency: 450hz 6.Employ industrial module (850/900/1800/1900mhz) 7.Can adjust voice volume by setting up from telephone set 8.Caller id display nal strength by led indicator 16.Imei change Carton