Hi,
Can you double check the below mentioned points has properly done in you HL8518 module:
• Set the APN: AT+WDSS=0,”your-apn”,”apn-login”,”apn-password”
• Check APN : AT+WDSS?
• Subscribe to all indications : AT+WDSI=8191
• Check current indication subscription: AT+WDSI?
• Activate 3 user agreements
• Check user agreements setting
• Initiate a DM session : AT+WDSS=1,1
• Received “starting DM session” indication (+WDSI:4)
• Received indication (+WDSI:6), DM exchange occurred between the module and AirVantage
• Received indication (+WDSI:8), DM session is closed
• Initiate once again a DM session
Note: there is no DM exchange, no (+WDSI:6) indication
Please refer to this document “AirPrime - HL Series - AirVantage Firmware Over-The-Air Guidelines - 2174110 - Rev1.0.pdf” for further more information.
Link : https://source.sierrawireless.com/resources/airprime/application_notes_and_code_samples/airprime_-hl_series-_airvantage_firmware_over-the-air_guidelines/
if you still face an issue , Please contact your Technical support in SWI to provide you the solution.
Thanks and Regards,
Rex