GSM Logs are hard to read. Here a few Tips and Tricks to make it easier.
The first row contains the raw data received in Hex.
Data received: 2B434D474C3A20312C302C22222….
This Hex encoded data will be conversted to text. The Resultat will be logged again:
OnTelnetData(); [8472]; Data received:
+CMGL: 1,0,"",154
069134660455102409D054A6B348050....
OK
„+CMGL“ is the answer to teh regular „AT+CMLG=4“ request - it basically is a „ Give me all (4) received messages from the memory in PDU mode“
The 1 is the Index of the message, in the next line you can find the PDU in 7bit format.
This can be decoded with an online PDU decoder like:
https://www.diafaan.com/sms-tutorials/gsm-modem-tutorial/online-sms-deliver-pdu-decoder/