nRF9160 AT&T Test SIMs

Question

Hey, 
 
 So I recently got some test SIMs from AT&T to use for our development. I'm trying to get them working with my nRF9160 dev kit but can't seem to get a connection to LTE. 
 AT&T requires me to configure my APN to "m2m.com.attz". So I'm running this AT Command: 
 
 AT+CGDCONT=1,"IPV4V6","m2m.com.attz" 
 
 When I run the link monitor and call the AT commands "AT+CFUN?" and press the "Search networks" buttons this is what it shows: 
 
 As you can see, its showing the network as "Verizon Wireless", however, the APN is configured for AT&T. Is there different configuration I need to do for AT&T? 
 
 - Jack

hmolesworth · Answer

AT&T uses bands 4 and 12 in the USA and Canada; band 12 is not (yet) approved or available for the nRF9160, which means you must use band 4. You can lock to band 4 with the following steps to avoid locking to Verizon's band 13: 
 The AT host sample started
AT+CGDCONT=1,"IPV6","m2m.com.attz"
OK
AT+CGDCONT?
+CGDCONT: 1,"IPV6","m2m.com.attz","",0,0
OK
AT%XBANDLOCK=1,"1000"
OK
AT%XCBAND=?
%XCBAND: (4)
OK
AT+CFUN?
+CFUN: 4
OK
AT+CFUN=1
OK 
 However .. we have not (so far) been able to connect to the AT&T network on band 4 even though some smartphones can connect to AT&T on band 4.