In many organizational setup, phone system is in place well before anything else. If a decision is made later to add customer service or support operations internally, it involves setting a full function contact center ACD. This ACD will handle among other things, all the IVR (Interactive Voice Response), Queues, Skills based Routing, time of the day scheduling and associated call center activities for the planned customer service or support. Once an enterprise level call center software is identified based on functionality, its inter-operability with the existing office PBX will determine if the call center agents can also be a part of the same extension schema for uniformity within the organization.
A modern contact center software should provide seamless integration to your existing office PBX. The office phone switch could be any modern PBX like an Avaya, a Shoretel or an Asterisk based Switchvox. The availability of such inter-operability will not only allow easy expansion with the agent phones behind existing office PBX but also keep options open for setting up distributed remote agents who can work out of different office locations within the same organization, all operating out of the same ACD queues.
A good ACD will not distinguish between remote agents and at-home agents. The voice end-points for an ACD agent can be a landline or a mobile phone. The key driver for providing remote and work from home agent capability is the ability of the call center ACD to treat different phone end-points as an integral part of the ACD agent voice end-point.