If you were at Astricon 2009, you would have know by now that the City of Amsterdam has a large VoIP deployment (20000 phones) based on Astium PBX which is based on Asterisk.
The solution, Astium PBX, by NeoNova. Due to restriction of brand name use, is known as 'IP Business Manager' within the City of Amsterdam. Astium uses Asterisk as the voice processor of the system, akin to a web application using Apache as the HTTP router, according to Neonova. The PBX supports a range of communication technologies including PSTN, ISDN, Dect, VoIP (SIP/IAX), Wi-Fi, GSM and fax. NeoNova offers the software as a free download and the software can be downloaded from www.astium.nl.