Displays your device's unique International Mobile Equipment Identity number. *#*#4636#*#*
Here are some popular secret codes for TECNO Spark 20: How to Use Secret Codes on TECNO Spark 20
If *#*#4636#*#* fails, try *#*#7378423#*#* (Sony code, but works on many MediaTek phones like the Spark 20). try *#*#7378423#*#* (Sony code