SIP Express Router (ser)
 I.   About SIP Express Router (ser)
 II.  Feature List
 III. About
 IV.  Obtaining Help
 V.   Contact, Licencing and More Information
  SIP Express Router (SER) is an industrial-strength, free VoIP 
 server based on the session initiation protocol (SIP RFC2543-bis). 
 It is engineered to power IP telephony infrastructures up to large 
 scale. The server keeps track of users, sets up VoIP sessions, 
 relays instant messages and creates space for new plug-in 
 applications. Its proven interoperability guarantees seamless 
 integration with components from other vendors, eliminating the 
 risk of a single-vendor trap. It has successfully participated in 
 various interoperability tests in which it worked with the products 
 of other leading SIP vendors.
 The SIP Express Router enables a flexible plug-in model for new 
 applications: Third parties can easily link their plug-ins with 
 the server code and provide thereby advanced and customized 
 services.  In this way, plug-ins such as SNMP support, RADIUS 
 accounting, or SMS gateway have already been developed and are 
 provided as advanced features. Other modules are underway: 
 Presence server, firewall control, and more.
 Its performance and robustness allows it to serve millions of users 
 and accommodate needs of very large operators. With a $3000 dual-CPU, 
 the SIP Express Router is able to power IP telephony services in an 
 area as large as the Bay Area during peak hours. Even on an IPAQ PDA, 
 the server withstands 150 calls per second (CPS)! The server has been 
 powering our free SIP site withstanding heavy daily load 
 that is further increasing with the popularity of Microsoft's 
 The SIP Express Router is extremely configurable to allow the creation
 of various routing and admission policies as well as setting up new 
 and customized services. Its configurability allows it to serve many 
 roles: network security barrier, application server, or PSTN gateway 
 guard for example.
 II. Feature List
 Based on the latest standards, the SIP Express Router (SER) includes 
 support for registrar, proxy and redirect mode. Further it acts as 
 an application server with support for CPL, instant messaging and 
 presence (IM&P) including a 2G/SMS gateway, a call control policy 
 language, call number translation, private dial plans and accounting, 
 authorization and authentication (AAA) services. SER runs on Sun/
 Solaris, PC/Linux, IPAQ/Linux platforms and supports  both IPv4 and 
 Most of SER features are implemented as plug-in modules. See
 README-MODULES for a description of modules available in
 ser distribution.
 III. About
c21b0b47 is a know-how organization spun off from Germany's national 
 research company FhG Fokus. One of the first SIP implementations ever, 
 low-QoS enhancements, interoperability tests and VoIP-capable firewall 
 control concepts are examples of well-known FhG's work. continues to keep this know-how leadership in SIP. 
 The access rate of the company's site, a well-known source of 
 technological information, is a best proof of interest. Thousands 
 of hits come every day from the whole Internet.
 IV. Obtaining Help
 We offer best-effort free support for ser. "best-effort" means 
 that we try to solve your problems via email as soon as we can, 
 subject to available manpower. If you need commercial support, 
 To receive feedback to your inquiries, we recommend you to subscribe 
 to the serusers mailing list and post your queries there. This mailing 
 list is set up for mutual help by the community of ser users and developers. 
 To participate in the mailing list, subscribe at the following web address: 

 Send your questions to 
 If you are concerned about your privacy and do not wish your queries 
 to be posted and archived publicly, you may post to 
 E-mails to this address are only forwarded to's ser development 
 team. However, as the team is quite busy you should not be surprised to 
 get replies with considerable delay. 
 V. Contact, Licensing and More Information
 For any additional information, send an inquiry to 
 Licensing conditions other than GPL are available on request. 
 Most up-to-date information is always available at our website,
 Particularly, it includes:
 - administrator's guide
 - installation guidelines (INSTALL)
 - download links
 - list of known issues (ISSUES)
 - etc.