DID Logic invested significant amounts in maintaining direct routes exclusively. We avoid the use of transcoding and we insist customers use G711u. That way, we keep the media uncompressed all the way from the originating SIP endpoint to the TDM circuit of the target carrier.
There are also pockets of HD-enabled destinations in Europe that justify the use of G722 high-definition voice to the PSTN. If your SIP endpoint supports G722 codec, and the carrier network you’re dialing allows HD subscriber handsets, we’re typically able to pass HD voice all the way.