When a prospect calls you to say that they are replacing their PBX, that sets the stage for a conversation. Most of those conversations will be about a cloud PBX (UCaaS) replacement service. That might be the wrong way to go.
It would be better for the Buyer and the Partner if the conversation were about a clean slate. Design the communications system from scratch.

What are they using now? Not just what PBX and options, but what apps.
- Are they using Zoom, Webex, or Slack?
- Are they a Microsoft shop?
- What CRM do you use?
- What other software runs their business? ServiceNow? Zendesk? etc.
- How do they hold meetings?
- Do they want a meeting transcript?
- What messaging or chat do employees use?
- Do they have an audio bridge?
- Do they utilize Dropbox or other file share?
- How do they sync and backup files?
- How do they collaborate on files with team members?
- How do they engage their customers? IVR? Web chat?
- Are they looking for some self-service options?
- Are social networks in play (omni-channel)?
- Do they have a call center?
- Is there a department that receives a lot of calls or makes a lot of calls?
If you start from scratch and build a system, the solution will be better for the Buyer. It doesn’t become “Here are 3 very similar UCaaS offers, which price do you like?” It becomes about outcomes.