Do you think the software team needs a communication plan ahead of a big modernization project? Have you ever provided your team with something like guidelines or talking points to help them discuss the project within the wider org?   

It requires a communication plan ahead of a big project; otherwise, how would they act when a problem arises? Or when an important message has to be conveyed immediately?

Use KIS (Keep it simple) in your communication plan, something the team will immediately understand, or they will have few doubts.

You can expand that communication plan to outside the team, so stakeholders will know and understand as much as possible, binding that communication plan with the one your team has.

Yes, they do, but I would call it an interaction plan, not a communication plan.
Communication is often perceived as one-directional, with you telling them, whereas it should be bi-directional. For two reasons:
- What you say won't be interpreted as you intended it, no matter how much crafting goes into your wording, and,
- You won't be able to anticipate every material concern or question the audience has. So, a feedback loop is essential.

In terms of the content, think CEMFS: 
- Case for Action (What bad things will occur if action isn't taken? This is the pain you are stopping or preventing.)
- Ends (The indicators of success, specific outcomes when complete.)
- Means (What will be done to produce those Ends)
- Feasibility (Display awareness of the barriers you have predicted, and the mitigating actions.)
- Safety (The negative side effects the program will trigger on you, them and others, and what you're doing to prevent or minimize them).

Note that the Means is the element that most audience members care least about. 
The Case for Action syntax is "Due to this, this and that, if we don't take successful action, bad things x, y, and z are likely to occur." Do Not frame it as an opportunity. "We have an opportunity to be better at this." 
Ends - list both tangible measurable/financial metrics and intangible benefits. 
Feasibility - on average, audiences foresee 44 reasons why your modernization program won't succeed. So cover at least half a dozen for credibility and say you realize there are more. 
Safety - the most emotional element and the one that will stop support. Groups average 11 reasons why your program will hurt them or others they care about (customers, partners). Again, list at least three and what you're doing about them.

Finally, don't close with the classical 'This is going to be Fantastic for all of us!'
Close with I4 - Invite them to privately express where they think what they've heard is Inaccurate, Incomplete, or Infeasible. 

Draw out the resistance now rather than suffer the consequences later. Your modernization program will not be On-benefit, On-time, or On-cost (OBTC). CEMFS and I4 are, however, playing a role in improving OBTC performance. You're creating a greater chance that the audience will be at the right end of the Resistance-Compliance-Commitment spectrum.

(Note: My company, SchellingPoint, an applied research company in group decision-making and coordinated action, developed CEMFS and I4. They are being used in Fortune 100 transformations, IT programs, government policies, and similar. We teach them in MBA programs and executive education. If they make sense to you, use CEMFS and I4 with any group to create action that is a better fit to the situation, more feasible, and endorsed. Feel free to raise any concerns, questions, or suggestions about their use. Michael)

In my experience, a communication plan is critical for a successful modernization project. It aligns stakeholders, builds trust, and drives momentum. Focus on:

 - Who: Identify key audiences.
 - Why: Tailor value messages to each group.
 - What: Share the roadmap and key milestones.
 - When: Communicate consistently and proactively.

Providing your team with clear guidelines and talking points helps ensure consistent messaging and empowers them to advocate for the project across the organization.