I ran a character who was sponsored by The Great Phoenix but didn't know it. All he knew was that he'd died in a fire, came back to life, and his magic worked differently ever since. Eventually, he realized there was some external entity granting him power, so he did a thaumaturgical ritual to get in touch and have a face-to-face meeting.
As for a more direct, faster way to contact a boss, I'd say that you probably shouldn't need to spend refresh on that. A good boss is keeping tabs on their emissaries anyway.
Some options:
* Do a summoning ritual, but with more of a "please show up" rather than "you WILL show"
* Call the boss's true name, or part of it.
* Changes Spoiler: Harry almost called Mab by accident after he became the Winter Knight simply by saying "Mab" a few times in the NeverNever
* Have a magic item provided by the boss. This wouldn't take item slots or refresh, it'd be more like a plot device or mundane equipment. It'd be the magical equivalent of a mob boss giving his underlings a cell phone number they can use to reach him.