Of course the backing service is not PHP. That would be a particularly poor choice for a high volume messaging statement. They originally wrote it in Erlang and

Of course the backing service is not PHP. That would be a particularly poor choice for a high volume messaging statement. They originally wrote it in Erlang and later rewrote it in C++. https://www.quora.com/When-did-Facebook-switch-away-from-using-Erlang-for-Facebook-Chat-What-was-the-reason-for-it-What-did-they-replace-it-with https://www.quora.com/When-did-Facebook-switch-away-from-usi...