You haven’t provided any info about your switch, IVR type etc. so it’s hard to help you. Anyway, there are several possibilities how to implement such functionality:
The one mentioned by Cavagnaro is the easiest one.
In TDM environment, you have no chance to implement such functionality within your softpohone application. It has to be done either on switch level (some switches like Avaya do support agent whispering) or on IVR level (e.g. GVP allows you to create separate leg for agent and merge it with customer’s leg once message is played to an agent)
In SIP environment, you can implement it within your softphone if SIP client is part of the application. Or SIP Server does support agent greeting functionality. Or the same option as for TDM - using IVR if such feature is supported.
You can do it with Softphone, but you’ll need a little black box that sits between the phone and headset and plugs into the soundcard on the Agent’s PC…
if we go with IVR level - customer call will be holding on to the GVP port until the call is delivered to the agent??
Yes, call stays on IVR. Please take into account fact that 2 IVR ports will be used during “agent whispering” phase as call to agent must be initiated on different IVR port.