Recently I am working on programming IoT Project, to receive messages from the phone. That part worked, but the problem that I am currently facing is that the message does not arrive fully because of the size of the buffer. That's why am asking a way to increase the buffer size. I have tried to change it manually, but the problem was not solved.

The Code is like

    char smsBuffer[250];
    // Retrieve SMS value.
    uint16_t smslen;
    // Pass in buffer and max Glen!
   if (sim800l.readSMS(slot, smsBuffer, 250, &smslen)) 
    smsString = String(smsBuffer);
  • 1
    Hey, welcome to the site! I've editted your question to improve the grammar, hopefully making it more clear for people trying to answer. If any of my edits conflicted with your intent, however, please do feel free to roll-back or edit to clarify. Thanks!
    – anonymous2
    Commented Jul 21, 2020 at 2:20

1 Answer 1


An SMS message has a maximum size of 160 chars.

While modern devices will allow you to send what look like longer messages they are just multiple messages that the devices concatenate together when received.

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