Dialing two extensions (not the question you think)

I’m looking for a way to dial two extensions simultaneously, with each call going on to it’s own context. So for example, say an extension dials extension 811, I want that call to go through as normal, except I want it trigger another context that does off and does it’s thing. Is there a way to do this through pure dial plan commands, or will have to go with custom scripts?

Any suggestions are welcome.