Aastra Telecom 800 User Manual

Page of 136
Voice over IP (VoIP)
SIP Telephony
68
information is available for NAT on an incoming RTP connection. To avoid this 
problem, the IP address of a workstation computer or telephone visible on the 
Internet is determined using a STUN server (STUN: Simple Traversal of UDP over 
NAT). You can ask your SIP provider for the STUN server’s IP address and port 
number. If you don’t need a STUN server, leave the SIP Provider field empty.
For direct SIP telephony using Aastra 800, only SIP IDs consisting of numbers 
for identifying subscribers registered with the SIP provider specified can be 
addressed 
You can integrate an external SIP connection in the Telephony: Trunks: Route 
menu into the route configuration. You can use a network provider rule to 
specify the routing of numbers within a specific range to use SIP telephony as a 
preference (see also PBX Networking, undeConfiguration starting on page 94).
You can configure SIP connections in the Configurator on the pages Telephony: 
Trunks: SIP trunks
 and Telephony: Trunks: SIP provider. Enter the technical 
attributes of a specific SIP provider, such as the IP addresses for the registrar and 
the STUN server under SIP provider. Under SIP trunks enter the information for 
an existing SIP account, such as the user name, password, assigned call number 
and the maximum number of simultaneous calls possible.
7.3.2 Internal SIP Subscribers
The Aastra 800 becomes available as the SIP server for internal SIP subscriber 
telephony switching services. SIP telephones connected via LAN or SIP programs 
installed on workstation computers can thus establish connections to all other 
subscribers or trunks connected to the Aastra 800. 
License Assignment
The number of possible SIP subscribers is determined by the number of licenses 
purchased. In order to provide you with the greatest possible flexibility regarding 
usage of available licenses, license assignment is dynamic via the “Floating 
license”. Using a user/password combination (“SIP log on”) you can have several 
SIP subscribers under the same call number. Only every new SIP log-on occupies a 
new license. The technical log-on process of a SIP subscriber with a valid user 
name and correct password is always successful. Only when a connection is estab-
lished is there an attempt made to occupy a license under the SIP log-on. If all 
licenses are occupied currently, the SIP subscriber can only make emergency calls.