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Hello Irvy,

If you can send a message with the SIM card in a mobile phone then at least you know that the SIM card works with the mobile phone. However, since it is an unknown error (usually error code 500 from the modem) the underlying cause of the error is not specified by the modem.

It it possible that the modem works on another network than the mobile phone (for instance the 3G network instead of 4G network) and that this causes the problem. It is also possible that the network does not understand the number format that Diafaan SMS Server uses to send the message, international number format, with a leading +, is usually the best option. There could be all sorts of other reasons why the modem is not able to send the message but without a clear error code finding the root cause is difficult.

Regards, Henk.

Hello Diego,

Unfortunately, CMS error 500 of the modem means that it reports an unknown error that tells you nothing about the underlying cause of the problem, just that it was not able to send the message. It could be that the connection to the mobile network is unreliable, that the SIM card does not have any SMS credits, that the mobile network blocks your messages or any other potential problem.

If unplugging the modem does not help then there is not much more you can try, but you might try to use the SIM in a normal phone and test if you can send SMS messages with the phone. Then you know at least that the SIM card is valid or not.

Regards, Henk