Anova/Linear regression

I have two datasets, one collected by one instrument, say A, and one by another, say B, at the same time. I need to use instrument B to calibrate instrument A results, but I am also wanting to see if the relationship between A and B changes between two different geographical locations that were measured.
I can run regression analysis between instruments A and B, but I also want to see whether this changes statistically between the locations.
I think an ANOVA is the best test for this but am unsure how to compare the two geographical locations.