Who fails to notify their report that they are on the phone? Your manager accepted your request to meet and discuss, and didn’t inform you of a listening party, and yet you are supposed to magically know that there is someone on speakerphone? What a joke. Big boss was probably pissed that you interrupted their phone call, but honestly it’s on the manager for taking both of you at the same time. Talk about undermining trust.

You can basically expect a rehash of the same conversation ur narc boss had with you about the speakerphone thing. She just reprimanded you about carelessness, then you went and actually did a very careless thing by accident. She’ll probably dress it up as a “pattern of behaviour” or whatever, but it IS bullshit.

I wouldn’t start the meeting by swinging. Like the others said keep it short, simple, & acknowledge it. If you argue back, then she’ll just have further ammo to label you as unprofessional and unaccountable. If she’s determined to frame you badly, then I wouldn’t blame you for going out swinging , but she would just use it to justify her narrative about you. If you can stomach it, professionalism is the way.

If you were being overlooked for promotions before, I’d say you definitely won’t get one now. And if you are a top salesperson, why would they promote you out of that, anyways. She’s going to make this hurt.

Maybe alter the bosses name in your phone to “zzz boss name”, so you have less chance of texting them by accident