One butron on Rainbow Smartphone to get call from hardphone

Hope there is feature for getting the call from Rainbow Smartphone by pressing a function or button. Currently to transfer incoming call to REX, involved too many steps:- - First you have to inform customer  - Then put customer on hold - Then dial the REX number which is programmed as speedial - Then you have to wait for RB Mobile to answer - Upon answered then you can then tranafer the call finally. This is not the way to "get call" from RB Mobile. Comparing with the Hardphone:- We can get call from hardphone, just be one button, why we cannot do it on the RB smartphone?