Is it customary to surprise applicants with a phone interview?
I'm applying for an internal promotion with my current employer. I had an appointment to call my potential boss to ask questions about the position (this is standard practice at my company). HR told me I would have a phone interview Tuesday.
When I called the boss today - surprise! He had HR on the line, and asked if I could do the phone interview today instead of an informal Q and A session with him as we had planned. I was caught off guard and didn't give the best interview. I'm not sure whether they did this on purpose as a stress test or what.
Do you think surprise interviews are a good way to produce qualified candidates? (I don't think so, but maybe I'm just upset because my interview didn't go well and I need to prepare further in advance or something.)
It's not uncommon, and it's not a good idea.
In fact, even worse than your situation, there's an epidemic of employers calling applicants and trying to phone-interview them on the spot, without any warning or advance notice. And many applicants are afraid to say that it's not a good time for them and to try to reschedule, because often they never get called back after that -- so you have people trying to do a phone interview outside the grocery store, frantically trying to remember which job this was at which company, with zero preparation.
It's obvious why this isn't good for the candidate, but it's not good for the employer either: Interviewing a candidate who just woke up or is late for a meeting or just hasn't had time to focus their brain on your needs isn't going to give you the most useful information about that candidate. The only exception to this might be if you're interviewing for a position that requires really compelling extemporaneous speaking, and even then I'm skeptical.
Frankly, operating this way is the sign of a employer (or at least their HR rep) just going through the motions, trying to check off boxes as if hiring is one more chore to get through, rather than something that's crucial to the success of the organization.
Now, your case is a little different. You had warning that you'd be talking to your prospective boss at that time but you were told to prepare for a different sort of conversation. That said, you probably should have prepared for the informal Q&A session in much the same way as you'd have prepared for a more formal phone interview, since the boss certainly could have had his own questions to throw right back at you. So I'd say that this is less about not giving you the chance to prepare and more about the fact that it can be mentally jarring to discover that the conversation you thought you were going to have is actually going to be a different type of conversation (in other words, it's more about mental preparation than substantive preparation).
I doubt they did this on purpose. That kind of conniving would be pretty unusual. What's more likely is that they're trying to move more quickly than than originally planned (or they moved too slowly at first and now need to make up for it) and when HR heard you were going to be talking with the manager that day, someone said, "Hey, let's do the phone screen at that time too so that we can keep this moving."
They should have told you in advance, but the fact that they didn't is -- I suspect -- less indicative of deliberate strategy and more indicative of the fact that employers often neglect to think about what kind of candidate experience they're creating, and what the impact of that experience is on their ability to hire the best candidate. That's a very, very common aspect of job-searching, and it's not in anyone's best interests.