|  | 101 | ==== AT Commands ==== | 
          
            |  | 102 |  | 
          
            |  | 103 | AT Commands are supported on one of the /dev/ttyUSB lines. | 
          
            |  | 104 |  | 
          
            |  | 105 | * [https://www.u-blox.com/sites/default/files/SARA-R4-SARA-N4_ATCommands_%28UBX-17003787%29.pdf u-blox SARA-R4/N4 series AT Commands Manual, Doc. No. UBX-17003787] | 
          
            |  | 106 |  | 
          
            |  | 107 | Radio Access Technology (RAT): | 
          
            |  | 108 | * R4 Series of Ublox Modems support NB-IoT and Cat-M1 and are enabled default. NB-IoT hasn't spread much in the USA so turning that off can speed up connections to CAT-M1 | 
          
            |  | 109 | {{{ | 
          
            |  | 110 | AT+URAT? # Query the radio access technology; 7 = Cat-M1, 8 = NB-Iot, 7&8 = both | 
          
            |  | 111 | AT+URAT=7 # Cat-M1 only | 
          
            |  | 112 | AT+URAT=8 # NB-IoT only | 
          
            |  | 113 | AT+URAT=7&8 # both | 
          
            |  | 114 | }}} | 
          
            |  | 115 |  | 
          
            |  | 116 | Operator selection: | 
          
            |  | 117 | {{{ | 
          
            |  | 118 | AT+COPS?  #is to check what network currently on | 
          
            |  | 119 | AT+COPS=? #is to check what networks are available | 
          
            |  | 120 | +COPS: (1,"311 480","311 480","311480",7),(2,"AT&T","AT&T","310410",7),(1,"313 100","313 100","313100",7),,(0,1,2,3,4),(0,1,2) | 
          
            |  | 121 | AT+COPS=1,2,"310410" #sets to AT&T | 
          
            |  | 122 | AT+COPS=1,2,"311480" #sets to verizon | 
          
            |  | 123 | AT+COPS=0,0 #To go back to automatic carrier selection (which is typically recommended) | 
          
            |  | 124 | }}} |