Emilio95,
Thank you for your message. It is good practice that a recommender includes a reachable phone number (either work or mobile), in case the school needs to connect. If the recommender is contacted, it might happen after the acceptance as part of the background check, or, in the worst case scenario, if there are red-flags and they need to verify beforehand. Therefore, proceed with the expectation that the school will contact the recommender.
Communication between AdComms and recommenders can be positive. If the AdComm is interested in admitting you but requires additional information, he/she might reach out to the recommender with a clarifying question. Remember, the AdComms are looking for ways to get a qualified person accepted. Therefore, a good recommender should encourage the AdComm to contact him/her so he/she can expand on what has already been submitted.
I hope this helps, and good luck!