Note that Grandstream has been going through rapid firmware changes, these are the last stable supported versions.
Release_GXP2130_1.0.7.97.zip Release_GXP2135_1.0.7.97.zip Release_GXP2140_1.0.7.97.zip Release_GXP2160_1.0.7.97.zip Release_GXP2170_1.0.7.97.zip