Will let you know which carrier belongs to the number you're calling BEFORE the call!
P.S. Now this prefix it's based on Italy standard, but you can modify it to fulfill your country requirements! (only numbers)
This app allows using the prefix 456, placed before the cell phone number, to know if who you're calling belongs to your own manager.
A recording, in fact, provide information on the operator of belonging and then start the call as usual (behavior may vary depending on the operator).
You can activate a request for every single call or leave enabled for all outgoing calls in automatic mode.
Latest version introduce possibility to hide your number before making call (#31#), in mode 'on request'. You can change this Italy prefix to your country specific code.
It works on all Android platforms from Eclaire to KitKat (2.1 -> 4.4).