Do Not Signal Loose Routing; Do Not Record-Route If Route Is Present - Snom 4S Administrator's Manual

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The setting in this field defines the destination, where the proxy
will send packets that do not stay in the private network. It is written in
the host:port format, for example "192.168.0.1:5060".

Do not signal loose routing

SIP messages flow from a user agent client (UAC) through a
number of proxies to another user agent, the user agent server (UAS).
This creates a path, the "routing path" that needs to be remembered for
further messages. For instance, if a proxy wants to carry out billing, it
needs to see all messages between the user agents to determine how
long the call took.
To do this, a proxy can insert a header into requests that
indicates that it would like to stay in the routing path in future requests.
Unfortunately, the first proposals for doing this did this in a complicated
way that can cause problems under certain circumstances. For this
reason, "loose routing", a new and better way of routing messages was
developed. For more information see the SIP standard RFC3261 or the
literature available on this topic. The snom 4S supports both routing
methods.
Although loose routing is mandatory for new SIP equipment
and is compatible with the old routing method ("strict routing"), some
equipment can still cause headaches. You can use the old-style routing by
turning this flag on. If you know your equipment does not have a problem
with loose routing, turn the flag off. If in doubt, it is better to turn this
flag on.
This setting may not be overridden by a script setting.

Do not Record-Route if Route is present

Some old equipment does not like to see both recorded routing
elements and an already available route path in the SIP header at the
same time. In these cases it might help to switch this flag on; however
the price of this is that the proxy is probably not in the route of future
requests any more. This means you will not be able to see a proper call
log even if the phone calls have been successfully made.
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