What with the gathering storm that is wideband telephony there’s a lot of rumbling about codecs going on at the moment. Such discussions usually include at least a couple of open source proponents wondering why Speex is not more widespread. It’s a very good question.
Speex most commonly shows up in soft phones. That’s nice, but soft phones have limited appeal. Most people prefer hardware of some kind. That’s where Speex implementations are few and far between. This is kind of the opposite of the situation that I found with G.722. In that case I found that hardware support was good and growing, but support for it in soft phones was lacking.