I am using a GSM/LTE module (EC21 Quectel) to send and recieve sms with HyperTerminal application on computer by at-commands. I can send sms to devices with the same operator (intra-operator), but not to any other operator (inter-operator). I can even recieve sms from other operators on my module, but when i try sending to them i get error.

the first number has the same operator as my module's simcard and the second one has a different operator

so does anybody know how to send an inter-operator sms? i would really appreciate it if anyone could help.

  • \$\begingroup\$ Error 350 is not described in the manual. Perhaps the subscription is not sufficient? (you need a different plan) \$\endgroup\$ – Jeroen3 May 14 '18 at 14:28
  • \$\begingroup\$ @Jeroen3 thank you for responding. yes it's "unknown error". can you explain what you mean by different plan? \$\endgroup\$ – Ali Sam May 17 '18 at 7:16
  • \$\begingroup\$ The provider you're with could limit your abilities, say if you have infinite texts between their numbers, but have to pay for other networks. If you do not have funds, you can't text. \$\endgroup\$ – Jeroen3 May 17 '18 at 7:59

Turns out the problem was because of my simcard monetary charge. for sending sms to diffrent operator, the network would charge me and my sim balance was zero. so i would get this "unknown error". so i charged my sim balance and the problem solved.


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