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Target release	1.0
Epic
Document status
Document owner	Alexander Feldt
Designer	Zsolt Erdei
Developers	Clemens Cramer
QA	Tita Petre

Goals

Align BLF and Extension behavior for PFKs on Snom desk phones by using XML definitions instead
- Improve user experience
- Improve performance

Background and strategic fit

BLF is a valuable feature for Snom customers, like enterprises who are looking to assist in connecting their customers to a live, available person as well as save business phone use time. Overall, it enables businesses to streamline their communication and better serve customers. BLF aka Extension monitoring has been utilized in numerous ways by businesses using Snom phone systems with multiple extensions. The current implementation appears to be kind of duplicated, but with a few little differences and erroneous behaviour.

Assumptions

Use case#1: A secretary's phone shall display the call status of the boss's line, allowing the secretary to know whether the boss is on a phone call or not. This will enable the secretary to make the decision to put the new caller on hold or let them through to the boss.
Use case#2: Call centers and customer support groups have also a need for BLF: it enables employees to see if their colleagues are free to take a support call or if their supervisor is on another line and unable to help another customer.
Use case#3: BLF is needed by teams working on a specific project: supervisors can monitor team members' extensions and vice versa so all team members are aware of each other's current status.

Requirements

#

Requirement title

Functionality

Importance

Notes

1

D8XX_BLF-XML_FR-1

On Snom IP phones acting as UAS, any SIP extension having an active subscription of its state changes, shall sent a notification SIP message (NOTIFY) to the UAC, when one of the following state changes occur:

from any state => terminated
from any state => trying
from any state => early
from any state => confirmed

Must Have

Fully implemented

2

D8XX_BLF-XML_FR-2

On D8xx IP phones, any PFK (programmable function key - physical or virtual) can be assigned to a function, which allows monitoring state changes of the configured SIP extension (UAS) on another IP phone. This function shall be called "BLF-XML". The following states of the monitored SIP extension (UAS) shall be processed and translated:

UAS state	Dialog state (NOTIFY)	Translated state
idle mode	terminated	idle
offhook / dialling	trying	busy
incoming call ringing	early/proceeding	ringing
incoming call accepted	confirmed	talking
outgoing call ringing	early/proceeding	busy
outgoing call accepted	confirmed	talking

Must Have

Partly implemented

3

D8XX_BLF-XML_FR-3

The assignment shall be configured either manually via web user interface (WUI) and/or phone user interface (PUI), and automatically via auto-provisioning (HTTP/TFTP setting server), SRAPS, or remote management (TR-069).

Must Have

Fully implemented

4

D8XX_BLF-XML_FR-1-1

On D8xx series, during an active subscription, state changes of the monitored SIP extension shall be visualized on both, PFK LED and PFK label.

Must Have

Fully implemented

5

D8XX_BLF-XML_FR-1-1-1

The PFK LED behaviour and colour shall be according to this table

Dialog state	terminated	trying	early/proceeding	confirmed
LED behaviour	off	on	blinking	on
LED colour	-	red	red	red

Must Have

Fully implemented

6

D8XX_BLF-XML_FR-1-1-2

The PFK label shall be composed of 3 areas:

(A) icon area	(B) name area
	(C) state area

Must Have

Fully implemented

7

D8XX_BLF-XML_FR-1-1-2-1

The label icon area (A) shall contain the following distinguishable graphical symbol, representing the state

Dialog state	terminated	trying	early/proceeding	confirmed
Processed state	idle	dialling	ringing	talking
Graphical symbol
Colour	white/green	white/orange	white/orange	white/red

Must Have

Partly implemented

8

D8XX_BLF-XML_FR-1-1-2-2

The label name area (B) shall contain the following text representing the display name or number (configurable) of the monitored / calling party

Dialog state	terminated	trying	early/proceeding	confirmed
roles	Monitored party	Monitored party >	Calling party > monitored party	Calling party <> monitored party
text	101 or Alex	101 > or Alex >	102 > 101 or Alice > Alex	102 <> 101 or Alice <> Alex
text colour	white	white	white	white

Must Have

Partly implemented

9

D8XX_BLF-XML_FR-1-1-2-3

The label state area (C) shall contain the following text representing the state

Dialog state	terminated	trying	early/proceeding	confirmed
text	idle	dialling	ringing	talking
colour	white	white	white	white

Must Have

Partly implemented

User interaction and design

User interaction

Dialog State

SIP message

XML definition

Design

UAS

UAC

UAS => UAC

UAS => Proxy => UAC

UAC

line seizing

monitoring

trying

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="..."
	state="full"
	entity="sip:101@...">
	<dialog id="..." >
		<state>trying</state>
	</dialog>
</dialog-info>

<general type="BusyLampField"/>
<initialization>
  <state value="off"/>
  <identity value="2"/>
  <variable name="subscr_uri" value="sip:104@192.168.137.1:5070"/>
</initialization>
<subscription type="dialog" to="<$(subscr_uri)>" for="$(subscr_uri)"/>
<NotifyParsingRules type="applies">
  <level1 translates_to='OK'>/dialog-info[@entity="$(subscr_uri)"]</level1>
</NotifyParsingRules>
<NotifyParsingRules type="state">
  <level1 translates_to="ringing">/dialog-info/dialog/state[.="early"]</level1>
  <level1-1 translates_to="calling">/dialog-info/dialog[@direction="initiator"]</level1-1>
  <level2 translates_to="ringing">/dialog-info/dialog/state[.="proceeding"]</level2>
  <level2-1 translates_to="calling">/dialog-info/dialog[@direction="initiator"]</level2-1>
  <level3 translates_to="offhook">/dialog-info/dialog/state[.="trying"]</level3>
  <level4 translates_to="in_a_call">/dialog-info/dialog/state[.="confirmed"]</level4>
  <level5 translates_to="free"/>
</NotifyParsingRules>
<NotifyParsingRules type="variable" id="call_id" state="ringing">
  <level1 fetch_attribute="call-id">/dialog-info/dialog[@call-id]</level1>
</NotifyParsingRules>
<NotifyParsingRules type="variable" id="remote_tag" state="ringing">
  <level1 fetch_attribute="remote-tag">/dialog-info/dialog[@remote-tag]</level1>
</NotifyParsingRules>
<NotifyParsingRules type="variable" id="local_tag" state="ringing">
  <level1 fetch_attribute="local-tag">/dialog-info/dialog[@local-tag]</level1>
</NotifyParsingRules>
<NotifyParsingRules type="variable" id="remote_uri" state="ringing">
  <level1 fetch_attribute="uri">/dialog-info/dialog/remote/target[@uri]</level1>
</NotifyParsingRules>
<action>
  <invite target="$(subscr_uri)" when="on press" states="calling, in_a_call, offhook, free"/>
  <invite target="$(remote_uri)" when="on press" state="ringing" request_uri="$(remote_uri)" replaces="$(call_id);to-tag=$(remote_tag);from-tag=$(local_tag)"/>
</action>

	101 >
	dialling

hangs up

monitoring

terminated

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="..."
	state="full"
	entity="sip:101@192.168.245.1">
	<dialog id="..."
		direction='initiator'
		call-id='...'
		local-tag=""
		remote-tag="">
		<state>terminated</state>
		<local>
			<identity display="B">sip:101@...</identity>
			<target uri="sip:101@...;line=...">
				<param pname="x-line-id" pval="0" />
			</target>
		</local>
	</dialog>
</dialog-info>

	101
	idle

incoming call ringing

monitoring

early

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="..."
	state="full" entity="...">
	<dialog
		id="..."
		direction='recipient'
		call-id='...'
		local-tag="..."
		remote-tag="...">
		<state>early</state>
		<local>
			<identity display="B">
				sip:101@...
			</identity>
			<target uri="sip:101@...;line=...">
				<param pname="x-line-id" pval="0" />
			</target>
		</local>
		<remote>
			<identity display="C">
				sip:102@...
			</identity>
			<target uri="sip:102@..."/>
		</remote>
	</dialog>
</dialog-info>

	102 > 101
	ringing

incoming call accepted

monitoring

confirmed

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="..."
	state="full"
	entity="sip:101@...">
	<dialog
		id="..."
		direction='recipient'
		call-id='...'
		local-tag="..."
		remote-tag="...">
		<state>confirmed</state>
		<local>
			<identity display="B">sip:101@...</identity>
			<target uri="sip:101@...;line=...">
				<param pname="x-line-id" pval="0" />
				<param pname="+sip.rendering" pval='yes' />
			</target>
		</local>
			<remote>
				<identity display="C">sip:102@...</identity>
				<target uri="sip:102@..."/>
			</remote>
	</dialog>
</dialog-info>

	102 <> 101
	talking

Incoming call terminated

monitoring

terminated

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="8"
	state="full"
	entity="sip:101@192.168.245.1">
	<dialog id="ef358a486677031ad4ecaac68710cef9"
		direction='recipient'
		call-id='b5c0006472bc-8x9sdw8f8qdr'
		local-tag="7196pmgjev"
		remote-tag="nyeqpi7kqy">
		<state>terminated</state>
		<local>
			<identity display="B">sip:101@192.168.245.1</identity>
			<target uri="sip:101@192.168.245.251:60158;line=caioqij3">
				<param pname="x-line-id" pval="0" />
			</target>
		</local>
		<remote>
			<identity display="C">sip:102@192.168.245.1</identity>
			<target uri="sip:102@192.168.245.1"/>
		</remote>
	</dialog>
</dialog-info>

	101
	idle

Outgoing call ringing

monitoring

early

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="13"
	state="full"
	entity="sip:101@...">
	<dialog
		id="..."
		direction='initiator'
		call-id='...'
		local-tag="..."
		remote-tag="">
		<state>trying</state>
		<local>
			<identity display="B">sip:101@...</identity>
			<target uri="sip:101@...;line=...">
				<param pname="x-line-id" pval="0" />
			</target>
		</local>
		<remote>
			<identity display="D">sip:103@...;user=phone</identity>
			<target uri="sip:103@...;user=phone"/>
		</remote>
	</dialog>
</dialog-info>

	101 > 103
	ringing

Outgoing call accepted

monitoring

confirmed

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="..."
	state="full"
	entity="sip:101@...">
	<dialog
		id="..."
		direction='initiator'
		call-id='...'
		local-tag="..."
		remote-tag="...">
		<state>confirmed</state>
		<local>
			<identity display="B">sip:101@...</identity>
			<target uri="sip:101@...;line=...">
				<param pname="x-line-id" pval="0" />
				<param pname="+sip.rendering" pval='yes' />
			</target>
		</local>
		<remote>
			<identity display="D">sip:103@...</identity>
			<target uri="sip:103@..."/>
		</remote>
	</dialog>
</dialog-info>

	101 <> 103
	talking

Outgoing call terminated

monitoring

terminated

NOTIFY
...
<?xml version="1.0"?>
<dialog-info
	xmlns="urn:ietf:params:xml:ns:dialog-info"
	version="..."
	state="full"
	entity="sip:101@...">
	<dialog
		id="..."
		direction='initiator'
		call-id='...'
		local-tag="..."
		remote-tag="...">
		<state>terminated</state>
		<local>
			<identity display="B">sip:101@...</identity>
			<target uri="sip:101@...;line=...">
				<param pname="x-line-id" pval="0" />
			</target>
		</local>
		<remote>
			<identity display="D">sip:103@...</identity>
			<target uri="sip:103@..."/>
		</remote>
	</dialog>
</dialog-info>

	101
	idle

Questions

Below is a list of questions to be addressed as a result of this requirements document:

Question	Outcome
(e.g. How we make users more aware of this feature?)	Communicate the decision reached

Not Doing

List the features discussed which are out of scope or might be revisited in a later release.