Hardware suggestion for 1000-1500 IP calls + E1-PRI Calls

Hello … Can Asterisk work reliably with, say 1000 - 1500 simultaneous IP calls and some E1/PRI calls too? Would it be stable with Asterisk 1.4 or 1.8? Right now, we use E1 / PRI only with Asterisk since from last few years for 1 0r 2 PRIs only. Currently we use Asterisk 1.4.44 with Digium / Synway & E1 - PRI. Which kind of Computer Hardware would be needed? We haven’t yet gone to such large scale yet, so we don’t know much about the required Hardware for such huge traffic. Please help me on it. Thanks in advance.