My A12 phone is intermittently blocking calls from two of my friends. Not all calls are blocked but my friend called me 6 times and got the engaged tone. I can call her.
I have cleared my phone cache and checked my blocked list but they don't appear on it as blocked.
There have been a lot of network issues with some providers lately- from my knowledge EE, O2 and BT had issues intermittently this week. I would check with your provider
