Seeing as "most" employees in a business situation have voicemail a number of employers do not even allow blind transfer to work on their companies PBX. they want to make sure that customers get through to a person, not voicemail unless they request that. I haven't seen a PBX that will bounce the call back to the person doing the transfer, it will normally ring for a preditirmined time then go to that persons VM.
If i as a customer reach you but the person i should be speaking to is "Mary", you transfer me to "Mary's" phone and after 3 or 4 rings I will go to her voicemail, not back to you or you will have to spend your time taking my message and then walk over to "Mary's" desk with it , if it's even in the same office.