SARA-R410M-02B IPCP failure when SMS is activated

0 votes
Dear Sir,

I am using SARA-R410M-02B to access a remote server via ppp link. Settings:

- SARA-R4 DTR pin connected to ground.

- SIM card working well with 4G, CAT M1

There is a problem with the IPCP layer when the SMS command is used before ppp link is established.

The traffic is like this:   

AT+CCLK? +CCLK: "18/11/08,03:28:37"

AT+CSQ +CSQ: 16,99

AT+CMGS="0449598788" >  Logger Message from unit 10801688, site ID: <None>, Signal Strength(0-100):51;.
+CMGS: 106

AT+CGDCONT=1,"IP","telstra.internet" OK
ATD*99# CONNECT 150000000

followed with some legal bytes for LCP and PAP, all correct. Then the system hits the IPCP layer.

The IPCP request packet is sent out properly. It is FF 03 80 21 01 09 00 0A 03 06. There is no response from the remote site for the request. The system keeps waiting until timeout and the ppp link dropped.

When CMGS command is not used, there is no SMS, the IPCP layer works well. There is no ppp link drop.

Why the SMS service is affecting the IPCP layer instead of LCP or PAP?

What could be the cause?

Thanks for your kind assistance.
by jshentu asked Nov 8, 2018
0 votes
You say "There is no response from the remote site for the request." Then why do you think it is a modem issue?

For PPP modem just a data pipe and application stack should handle this correctly.

Not sure how SMS is affecting this unless there is some re-configuration on the network when SMS is sent.
by grumpy answered Nov 20, 2018
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