RM520N-GL unable to send SMS

Hi team,

We acquired RM520N-GL from Digikey. during testing, we are unable to send outgoing SMS.

this command is example from procedure (8.8. AT+CMGS Send Message)

[2026-01-12_14:02:39:552]AT+CMGF=1
[2026-01-12_14:02:39:552]OK
[2026-01-12_14:02:44:122]AT+CSCS=“GSM”
[2026-01-12_14:02:44:122]OK
[2026-01-12_14:02:50:957]AT+CMGS=“62811xxxxxx”
[2026-01-12_14:02:50:957]>
[2026-01-12_14:02:53:876]> TEST
[2026-01-12_14:02:55:008]+CMS ERROR: 305

please provide assistance.

RM520N-GL
RM520NGLAAR01A08M4G_01.206.01.206

please also confirm if there is latest firmware or 01.206 is the latest.

Dear @morpig
Do you set Service Center Address?
Or do you test this SIM card with other device? Is SMS working?