A5/3 is not deployed in GSM networks
The 3GPP has specified the Kasumi-derived A5/3 cipher for use in GSM networks. This would significantly increase the confidentiality and security of the GSM network, since it avoids the known-weak and known-broken A5/1 cipher. The passive A5/1 key-cracking attacks would no longer work.
In order to use A5/3, both the MS and the BTS will have to implement the A5/3 cipher, and the BSC will have to configure the BTSs to actually use it.
Many modern phones (whether 3G or not) support A5/3 operation on GSM and indicate this capability in their CLASSMARK.
However, none of the networks we have seen are using A5/3 on GSM.
Thus, the operators and/or equipment manufacturers are actively preventing a higher level of security and confidentiality.