How to check account of SIM in Fastrack supreme 20

IoT Gateways Legacy FX/FXT series
25

awneil was wrigth: +CUSD: is an unsolicited response. :blush:
Additionally you have to use:

adl_atUnSoSubscribe("+CUSD: ", atUnSoHandler);

Where atUnSoHandler has the same functionallity than atRspHandler in your original code.