You can have it all. Now. A few years ago, things were different. You could have it all, but you would pay dearly for the privilege. Traditional phone switches (PBX) provided extensions and connectivity to your telco.
Once you had paid the price for PBX functionality, you had access to a full set of PBX features, such as
You can do a lot these days with your laptop, an Internet connection, and an idea. When that idea involves customer service, inbound sales or even an information line, there's no reason it has to wait. Ten years ago, you'd have to buy expensive hardware and wire it into a rack somewhere.
When you have a previous relationship with your client, it's important that this be reflected in the customer experience. Often, the data concerning the client is available in a separate system from your call center ACD software. Keeping data in a central location can be an effective way to ensure data stays in a consistent state, rather than being replicated and updated separately. It's important to make sure it's available when and where needed.