E&M Abode Signaling
PBXs congenital by altered manufacturers can announce on-hook/off-hook cachet and telephone
line admission on the E&M interface by application any of three types of admission signaling:
■ Immediate-start: Immediate-start, as illustrated in Figure 3-12, is the simplest
method of E&M admission signaling. The calling ancillary seizes the band by activity off-hook
on its E lead, waits for a minimum of 150 ms and again sends abode advice as
DTMF digits or as dialed pulses. This signaling admission is acclimated for E&M tie trunk
interfaces.
Figure 3-12 Immediate-Start Signaling
■ Wink-start: Wink-start, as apparent in Figure 3-13, is the best frequently used
method for E&M admission signaling and is the absence for E&M articulation ports. Winkstart
was developed to abbreviate glare, a action begin in immediate-start E&M, in
which both ends attack to appropriate a block at the aforementioned time. In wink-start, the calling
side seizes the band by activity off-hook on its E lead; it again waits for a abbreviate temporary
off-hook pulse, or “wink,” from the added end on its M advance afore sending
address advice as DTMF digits. The about-face interprets the beating as an indication
to advance and again sends the dialed digits as DTMF or dialed pulses. This signaling
is acclimated for E&M tie block interfaces. This is the absence ambience for E&M articulation ports.
Chapter 3: Routing Calls over Analog Articulation Ports 143
Sending About-face Accepting Switch
Sending about-face goes
off-hook.
Off-Hook
On-Hook
Off-Hook
On-Hook
150 ms DTMF Digits
Sending about-face waits a minimum of 150 ms before
sending addressing.
Receiving about-face goes off-hook
after affiliation is established.
Sending About-face Accepting Switch
Sending about-face goes
off-hook.
Receiving about-face goes briefly Wink
off-hook for 140 to 200 ms.
Off-Hook
On-Hook
Off-Hook
On-Hook
DTMF Digits
Sending about-face waits a minimum of 210 ms before
sending addressing.
Receiving about-face goes off-hook
after affiliation is established.
Off-Hook
On-Hook
Figure 3-13 Wink-Start Signaling
■ Delay-start: With delay-start signaling, as depicted in Figure 3-14, the calling station
seizes the band by activity off-hook on its E lead. After a timed interval, the calling side
looks at the cachet of the alleged side. If the alleged ancillary is on-hook, the calling side
starts sending advice as DTMF digits. Otherwise, the calling ancillary waits until the
called ancillary goes on-hook and again starts sending abode information. This signaling
approach is acclimated for E&M tie block interfaces.
144 Authorized Self-Study Guide: Cisco Articulation over IP (CVOICE)
Sending About-face Accepting Switch
Sending about-face goes
off-hook.
Receiving about-face goes
on-hook.
Off-Hook
On-Hook
Off-Hook
On-Hook
DTMF Digits
Sending about-face waits for accepting about-face to go
on-hook afore sending addressing.
Receiving about-face goes off-hook
after affiliation is established.
Off-Hook
On-Hook
Figure 3-14 Delay-Start Signaling