I’ve got the GT7500 modem work reliably with Verizon, Rogers and AT&T, except for the AT&T with a Kore SIM. In that case the first TCP session works, but the second one fails to open, and the only fix is to reset or power-cycle the modem. Am I doing something wrong? Below is the summary of the interaction between the modem and the host.
+++
ATH => OK +KTCP_DATA: 1,
AT+KTCPCLOSE=1,1 => OK
AT+KTCPDEL=1 => OK
==== second attempt fails ====
at+KTCPCFG=1,0,"<IP address>",<port> => +KTCPCFG: 1
AT+KTCPSTART=1 => +KCNX_IND: 1,4,1 +KCNX_IND: 1,1,0 +KTCP_NOTIF: 1,5
+++
ATH => OK
AT+KTCPCLOSE=1,1 => ERROR
AT+KTCPDEL=1 => OK
It looks like, while the PDP context “connected”, the second TCP session opening fails with a generic “TCP Error”. To emphasize, this exact command sequence works fine in all other setups.
Which firmware version are you using? If you are not on the latest firmware, please download the latest one and retry.
You can get it here AirPrime HL7588 Firmware
Please provide the output of below commands:
==== first attempt ====
ATI3
AT+CGDCONT?
AT+CGREG?
AT+CEREG?
AT+CGACT?
AT+CGPADDR
AT+KCNXCFG=1,“GPRS”,“C1.KOREM2M.COM”
AT+KTCPCFG=1,0,"", => +KTCPCFG: 1
ATH
AT+KTCPCLOSE=1,1 => OK
AT+KTCPDEL=1 => OK