327
• DSS1/QSIG user signaling, adopted on the D channel between ISDN user and network
interface (UNI). It has a data link layer protocol and a Layer 3 protocol used for basic call
control.
• ITU-T R2 signaling, which includes digital line signaling and interregister signaling. Digital line
signaling is transmitted in TS16 (ABCD bits) of E1 trunk. It conveys status information about E1
trunks to describe whether the trunks are occupied, released, or blocked. Interregister signaling
conveys information about address, language and discriminating digits for internal calls, echo
suppressor, caller properties and callee properties in multi-frequency compelled approach
(forward and backward) in each timeslot.
• Digital E&M signaling, similar to R2 signaling. It transmits E (recEive) and M (transMit) call
control signals similar to analog E&M signaling in TS16, alignment signals in TS0, and voice
signals in other timeslots. In digital E&M signaling, when an E1 trunk detects and sends
connection signaling, it looks at the signal in TS16. Digital E&M signaling provides three start
modes, immediate, wink, and delay, to adapt to different devices for more reliable connection.
• Digital LGS. Digital loop start signaling is used between telephones and switches to identify the
off-hook/on-hook state, while ground-start signaling is used between switches. They differ in
that the two parties in conversation must check grounding state before closing the line in the
ground-start approach.
Fax function
The fax function is available on E1/T1 voice interfaces to set up fax channels and transmit/receive
fax data.
Protocols and standards
E1/T1 voice supports SIP and recommendations in ITU-T H.323 framework, and G.711, G.729, and
G.723.1 Annex A (5.3 K and 6.3 K) in ITU standards.
Table 265 Protocols supported by E1/T1
Item E1 voice T1 voice
Framing format CRC4, non-CRC4 SF, ESF
Line coding
format
HDB3, AMI B8ZS, AMI
Introduction to BSV interface
The BRI S/T voice (BSV) interface supports simultaneous transmission of voice and data, can
receive, send, compress, de-compress digital PCM voice traffic, and realizes VoIP function through
other WAN interfaces of the router.
Generally, a BSV interface is used to connect an ISDN digital telephone. Also, it can be used as a
trunk interface connecting to a PBX digital trunk. If it cooperates with an FXS or FXO interface, a
BSV interface can realize flexible routing policies for voice callings.
Configuring digital link management
You can click the link of a digital link name to access the page displaying the link state. For more
information, see Displaying ISDN link state.
Configuring VE1 line
Select Voice Management > Digital Link Management from the navigation tree, and then click the
icon of the VE1 line to be configured to access the E1 parameters configuration page.
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