Integration of third-party statistics data

I have self-made call-tracker service and I want to integrate its data to matomo analytics system.
In matomo I added Custom Dimension (type Visit) that correlate to cookie that my call-tracker service create when user visits my website.
So now I’m able to identify each visit in matomo and call-tracker and connect them to each other. I want periodically to load some data from my call-tracker database (e.g. is this visit gave me a call or not, time of phone call, duration of phone call etc) - total up to five values.
What is the most convenient way to do that? Should I use Custom Dimension for each of call-tracker values or maybe there is some other more appropriate way?