Q- what is 3gpp recommendation for the air interface encryption algo?
1- A/3 is the new standard, but the standard encryption recommended is A5/1.
Q- is this feasible within a vendor’s MSC and BSS that MSC and BSS are configured with different algorithms?
2- nope. All equipment support A5/1 by default. Now, one equipment may support a5/3 (the new one), but not the other equipment. In this case, both equipment will switch down to a5/1.pix