As by my sibling comment, the language was called C+@, formely Calico.

https://www.drdobbs.com/cpp/the-c-programming-language/18440...

Actually AT&T did create a language for networked systems, cleverly named C@+, or C+@, don't recall the name properly.

Dr. Dobbs Journal had an article about it, back in the 90's when they run a piece of possible C++ replacements.

If I dig out my archive I can post the information as reply later on.