I am a software engineer. Sometimes, the project manager in my team will randomly call me out of nowhere on our communication software, without asking first if it's ok to interrupt me. They usually will have questions about planning of upcoming projects, which they want my opinion on.
I of course have no problems answering those questions, and I don't have any issues with my colleague in general (I like them as a person and find them mostly agreeable to work with), I just have issues with this habit of calling me without checking if it's ok to do so beforehand.
Receiving a call on my computer, with the consequent ringing and notification popup, while I'm looking at a complicated piece of code is a huge disruption to my concentration, and after that has happened it can take me quite some time to regain it. Also, I generally feel like 99% of those questions could be just asked through a chat message. The topics are (almost) never that urgent.
How can I politely let them know that these calls are actually impairing my productivity, and that I would prefer that any call is preceded by a chat message, to check if it's ok to call me in the first place? This would allow me to switch my mindset and my focus at my own pace, rather than having to randomly jump from whatever I was doing to the new topic at hand at the drop of a hat.
Just to further clarify, it's not (only) having to answer that bothers me, what is enough to disrupt my concentration is the incoming call by itself.
It is not an option for me to simply flat out ignore all calls, because while most calls aren't that urgent/important, some (rare ones) are. Also, I am pretty sure not answering when a colleague calls would make me look impolite or unreliable, and I obviously don't want that.
So, how to broach the subject in a polite and friendly way? My main concern is that the message shouldn't come across as "I don't want to be bothered/annoyed by you"...