Enquiry on USSD EC20F

Hi may I know why does I only receive OK response from the following command AT+CUSD=1,‘123#’?

I had tried the USSD with a phone and it works.

Please give me some advise and help.

Thank You


I wasn’t able to find detailed documentation on the atcom command you’re using.

I suspect it’s satisfied when it receives the “OK” response.

This behaviour is unsuitable for the AT+CUSD command, because the USSD payload is delivered by the modem as an unsolicited +CUSD: result after the “OK”.

Maybe try picocom instead of atcom as a test.

Here’s an example from my logs:



+CUSD: 1,"Main Bal: $240.01
Exp: 10 Jun 2019

Thank for you help snowgum.

However picocom doesn’t work as well.

The picocom command works differently. You don’t put the AT command on the command line.

You open the port with picocom for interactive dialog, like so:

picocom /dev/ttyUSB2

With the port open, you can issue AT commands and see the responses.

Maybe start with the simplest AT command, which is AT

It will return “OK” (that’s all it does). Then try other AT commands.

Use the two-character sequence <ctrl>A <ctrl>X to exit picocom.