Siemens HiPath 4000

HiPath 4000 is the leading converged communications platform
f or medium and large enterprises that provides business process
and workflow integration, high availability, strong security, powerful performance and cost-effective communications. HiPath 4000 already 
has more than 15 million users in more than 80 countries worldwide.
Providing scalability from 300 to 12,000 users on a single system and
up to 100,000 users in a network, the modern architecture supports
a variety of flexible deployment models and offers standards-based
integration and interoperability with business-critical applications and
 systems. HiPath 4000 supports analogue, digital, IP and SIP based
users.