Appendix A. More About SIP

Configuring the PBX

The PBX must be configured to accept registrations for your SIP domain. How you do this depends on the PBX you are using. Some PBX:s accept all domains.

Configuring the DNS Server

To make other SIP users find your SIP domain, you need to configure your DNS (or rather, the DNS managing the domain).

One way of doing this is to add an A record for the domain, and point it to the Telecommuting Module. With this solution, you need to have a SIP domain that is not used for anything else. An example of a SIP-specific domain would be sip.3com.com.

If you want to use the same domain for all your communication (like 3com.com), you need to add an SRV record to the DNS server instead, and point it to the Telecommuting Module. The SRV record is used specifically by SIP devices.

This is an example of an SRV record:

_sip._udp

SRV

100

0

5060

tess

_sip._tcp

SRV

100

0

5060

tess

_sips._tcp

SRV

100

0

5061

tess

This SRV record is entered into the zone file for the SIP domain. It points to the host tess, which is supposed to be a computer under the same domain (tess.3com.com) - in this case the Telecommuting Module.

If you don’t want to use all transports, you can enter just the lines for the transport you want to allow (like only the TCP line).

Configuring the SIP Clients

SIP clients that can be configured to use a domain name only need to use the DNS which handles the domain.

SIP clients that need to be configured with an (additional) IP address should use the IP address of the registrar when located on the LAN, and the outside IP address of the Telecom- muting Module when located anywhere else.

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