Engineers at Unibot successfully bypassed regional network restrictions on the Quectel RG255C-GL modem, which is installed in the Agibot X2 Ultra robot. The device previously failed to register in Russian LTE networks despite detecting them.
The team identified a specific function within the modem's firmware that performed a check on the Mobile Country Code (MCC). By modifying a single bit in the radio code, they disabled the restriction for the Russian MCC 250 without affecting other regional settings.
The process involved extracting firmware files, analyzing the CLADE compression format, and updating the MBNv7 container. The team successfully signed the modified image using a local certificate chain, which the modem accepted without requiring a full Secure Boot bypass.
Following the firmware patch, the modem successfully registered with the Tele2 network (PLMN 25020) using a T-Mobile SIM. The device established an IPv4 connection and passed connectivity tests via the wwan0 interface.
