CID Prefix should not be used with Inbound Routes if you are using Dynamic Routes to route call flow and you are evaluating the CID Name with FreePBX on Asterisk.
Evaluating CallerID (CID) based solely on the number is a design flaw of FreePBX. At FreePBX's heart it relies almost exclusively on the CID number instead of the CID name. Their design makes little allowance for evaluating the CID name. The Dynamic Route module changes this, as it allows you to evaluate the caller by looking at the name, and then allows you to route based on that (on either that alone or together with the number). There's a feature in the Inbound Route and the Ring Group (and maybe others) that allows you to set the CID Prefix (their description is "You can optionally prefix the CallerID name. ie: If you prefix with "Sales:", a call from John Doe would display as "Sales:John Doe" on the extensions that ring.").…