DBC 422
AND
DBC 425
57
1531-DBC 422 02 Uen B3 2013-12-02
7.21.1.2
Registration towards the gatekeeper
At log on the phone promts the user to enter the extension number and
the password or PIN. If the user do not have a password or PIN, the
phone tries to log on to the insecure UDP port1719.
In case the IP phone tries to log on securely but the establishment of the
TCP connection fails, this is interpreted as the gatekeeper does not
support secure mode. The phone shall back off to RAS over UDP. The
possibility to back off to UDP is managed via a parameter in the config-
uration file, see the description for
CONFIGURATION FILE FOR DBC
42X
.
During the TLS negotiation, the server will authenticate itself by using a
digital certificate, see 7.21.1.1 Certificates on page 55.
In the configuration file there is an option whether the client shall validate
the server certificate or not. If the option is enabled but the server does
not have a certificate that is signed by one of the Certificate Authorities
supported in the phone or if the certificate has expired, it will result in a
failed authentication.
There are two options in the configuration file for the password:
•
Do not store the password in the phone: The user needs to re-enter
the password each time the phone registers towards the gate-
keeper, that is, after power failure, network failure, update of firm-
ware. This option is not available for the DBC 420 phone, which do
not have the log on option from the key pad.
•
Store the password in the phone in the same way as when not
using TLS, that is the user only needs to re-enter the password
after the phone is manually logged off or when the phone has been
logged off after the extension number is used by another IP
terminal.
7.21.1.3
Call Setup and Call Control
When the IP phone that is registered securely, sets up a call using H.225
Q.931 messages, it sends the requests to TCP port 1300 instead of TCP
1722.
In order to negotiate the capability of the call, an H.245 negotiation takes
place on a new TCP connection between the terminal and the gate-
keeper. The TCP port to be used is negotiated during the H.225
signaling. The TCP connection can be initiated by either part. This TCP
connection is protected by means of TLS as well.
This implies that during a call there can be three TCP connections
existing between the terminal and the gatekeeper.
