IMHO when users scale up to such levels, Asterisk falls short, I made a c ouple large implementations and the best approach is using OpenSer as SIP engine (along with his own media proxy if required by your network schema) and use Asterisk as "Vertical Services Provider", such as email, IVR, in general, expliding the benefits Asterisk overachieve, including TDM interconnection as well.<div>
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