I don't think it was HIPPA Bridge, but there is a large hospital system in the city that encouraged doctors & nurses to download this secure HIPPA approved app (if that makes any sense). There were three different types of doctors: the ones that really caught on and responded to messages in a timely manner, the ones that had the program installed on their phone but never set up notifications and only opened it once every few days, and the last type still used pagers.
I work at a couple different LTACs. At one of them the charge nurse calls/text the doctor from a company cell phone for all the nurses, so the floor nurses don't contact the doctors themselves. Texting at that LTAC was used for simple or small issues, for example patients who want OTC medications, diet changes, x-rays for line/tube verification, etc.
At the other LTAC I asked the charge nurse for a Dr.'s phone number, she gave it to me and told me that he prefers texting for small issues. I asked her for the phone & she gave me a strange look and told me that most nurses just use their personal cell phones. The LTAC had 20-30 patients split between 2-3 doctors. The nurses would either refer to the patient in the text message by room number or initials. A few years ago in nursing school we were taught that room number is not a patient identifier/PHI and is one of the safest ways to refer to a patient when talking with staff where information might be overheard. Also on all of our nursing care plans we used patient initials.