It took hours to make sure the signal was secure. Uhura would have been able to do it a fuck of a lot faster, but this isn't something Jim's mentioning to any of them. Especially in case it doesn't work. He'd considered what sort of message to leave for hours before he'd started working on opening a secure channel. Leaving details or mentioning the Nexus was right out for any number of reasons, so this is the safest way.

Jim keys in the sequence for his home in Iowa and waits for the prompt to send a message. It's short, painfully so. Just a frequency for whoever finds the message to call him back on. That way he'll know who he's talking to before he says anything he shouldn't. It's the safest way.

This isn't the sort of thing he can clue his counterpart in on, even if it means staying here.

Jim sends the message and steps away from the terminal. He hopes it will be enough.