Three phases, because there are only three.
Most firms publish five to seven. The extra ones exist to fill a diagram. Design, develop, refine is the whole of it, and the tagline is the process rather than a slogan sitting on top of one.

Design
Two to four weeks
Scoping done by the people who will be held to the estimate, so the number that reaches you has an owner.
The engineers scope it
The people who write the estimate are the people who write the code. That removes the handover where a salesperson's number becomes an engineer's problem, and it is the single biggest reason estimates drift.
We work against your data
Interface work happens against the real data model, not a happy path drawn in a design tool. If a screen cannot be populated from what your systems actually return, we would rather find that out in week two than in month four.
You get a scope you can refuse
Design ends with a written scope, a sequence and a shape of team. It is a document you can take to another firm. If the answer is that the project should not happen yet, that is a legitimate output.
Develop
Two-week increments
Working software in week three, demoed to you, shipped behind flags. Not a status deck.
Increments you can see
Every two weeks there is something running that you can click. Progress is demonstrated rather than reported, which makes it much harder for a project to be quietly late.
Flags before features
Work ships dark and gets switched on. The path back is tested before the path forward is merged, because in payments and healthcare a bad deploy is a queue of real consequences, not a rollback.
Your definition of done
Embedded work runs on your review process and your standards. If we apply ours instead, we hand you debt you did not choose and cannot maintain.
Refine
Ongoing
The squad stays. Most of our work is month thirteen onward, because that is where a platform is actually decided.
The same people
Continuity is the product. An engineer who was in the original scoping conversation still knows why a decision was made two years later, and that knowledge does not survive a staffing change.
Numbers in the monthly report
Lead time, release cadence and uptime go in the report whether or not they flatter us. A metric you only see when it is good is not a metric, it is marketing.
Written to be handed over
Everything is built on the assumption that your team will own it eventually. Documentation and runbooks are part of the work, not a phase at the end that gets cut.
Start a conversation
Tell us what you are trying to ship.
You will get a reply from an engineer, not a form handler. If we are not the right firm for it, we will say so and tell you who is.