I am trying to use a Verizon version of the GL7500 with our product and sometimes it connects, but often gives an ERROR. Sadly, the docs and the threads have not been helpful so far.
Here is a typical annotated sequence of commands and responses:
AT+CGREG? → +CGREG: 0,1 // check registration status: registered
AT+KTCPDEL=1 → ERROR // delete previous TCP session 1, if exist. (There was none in this case)
at+cgdcont? →
+CGDCONT:
1,“IPV6”,“vzwims”,“FE80:0:0:0:E055:A0D9:436C:8C1E”,0,0,0,0,0,0
2,“IPV4V6”,“vzwadmin”,"",0,0,0,0,0,0
3,“IP”,“PWSDIA.GW8.VZWENTP”,“0.0.0.0”,0,0,0,0,0,0 // this is the APN to be used
4,“IPV4V6”,“VZWAPP”,"",0,0,0,0,0,0
OK
AT+KCNXCFG=3,“GPRS”,“PWSDIA.GW8.VZWENTP” → OK // Configure GPRS connection for the context 3 (why isn’t this preserved on power cycle, anyway???)
at+KTCPCFG=1,0,“123.456.789.012”,12345 → +KTCPCFG: 1 // Create a client TCP session with ID=1, the IP and port are made up in this example, but the real ones work with other modems
AT+KTCPSTART=1 → ERROR // start a TCP Connection: supposed to get CONNECT, among other responses, get ERROR instead
Again, it doesn’t always fail, sometimes I get the expected CONNECT message.
What is going on and how do I fix it? Is there some hidden timing issue?
Thanks in advance!