Hi folks,

to share a finding: the question was whether 2G and 3G cells may share location area codes.

A glance at some (mostly anonymized) live data from GSM cell monitoring hardware, in use by one of our customers, answers that quite clearly:

Network MCC MNC LAC CID Type Band

FirstOperator 123 4 678 C669 GSM GSM900 FirstOperator 123 4 678 CF5A GSM GSM900 FirstOperator 123 4 678 CF2A GSM GSM900 FirstOperator 123 4 678 C695 GSM GSM900 FirstOperator 123 4 678 CF30 GSM GSM900 FirstOperator 123 4 678 CF58 GSM GSM900 FirstOperator 123 4 678 6869 UMTS UMTS2100 FirstOperator 123 4 678 C69B GSM GSM900 SecondOperator 123 5 9AB DEEF GSM DCS1800 SecondOperator 123 5 9AB E15D UMTS UMTS2100 SecondOperator 123 5 9AB E163 UMTS UMTS2100 SecondOperator 123 5 9AB E080 GSM DCS1800

LACs are shared across 2G ("GSM" here) and 3G ("UMTS") technologies, only the cell IDs are guaranteed to differ.

Happy hacking,

~Neels