Section 10.2.4. Subscriber, CO/Tie Trunk Circuits in Access Points

10.2.4. Subscriber, CO/Tie Trunk Circuits in Access Points

In an IP distributed access point, all subscriber line and CO/tie trunk modules can be used, with a few exceptions which are described in the OpenScape 4000 Technical Upgrade Plan

When using analog access modules which also require a ring generator, the following must be taken into consideration:

In the 19“ access point AP 3500 IP and the AP 3505 IP expansion box, only RGM type ring generator modules (S30807-Q6141-X or S30122-K5929-X) can be used, not RG modules. The AP 3505 IP expansion box requires its own RGM independently of the AP 3500 IP basic box, if analog access modules are to be operated in it.

IMPORTANT:

Trunk connections between access points in the same system or between a central system and its access points are not permitted.

Figure 184. Tie connections are not permitted within a system

With the configuration in an IP distributed access point, all circuits are given additional parameters to govern their handling of Voice over IP. These IPDA classmarks are:

Table 41. IPDA classmarks

Classmark	Sprache/ Language	Beschreibung/ Description
EC	d	Echo Cancellation
EC	e	Echo Cancellation
G711	d	Codec Typ G.711
G711	e	Codec Type G.711
G729	d	Codec Typ G.729A
G729	e	Codec Type G.729A
G729OPT	d	Codec Typ G.729A - optional
G729OPT	e	Codec Type G.729A - optional
INIT	d	stellt Default-Einstellung wieder her
INIT	e	restores default setting
KEINE	d	schaltet alle Classmarks aus
NONE	e	turns all Classmarks off
ML	d	Multiple Listener - Ansage wird auf einer Verbindung übertragen und im Access Point an meherere Sätze geschaltet. *) nur für Ansagegeräte/MOH
ML	e	Multiple Listener - Announcement is transmitted on a single connection and switched to multiple ports in the Access Point. *) only for Announcement Devices/MOH
VAD	d	Voice Activity Detection
VAD	e	Voice Activity Detection
VIAHHS	d	Payload über Zentralsystem *) nur für Ansagegeräte/MOH
VIAHHS	e	Payload via central system *) only for Announcement Devices/MOH

Details of the procedures that are switched with classmarks can be found in:

Voice Compression - Section 4.2 on page 4-79 in the document “Gateways HG 3500 and HG 3575”
Voice Activity Detection (VAD) - Section 4.3 on page 4-81 in the document “Gateways HG 3500 and HG 3575”
Echo Cancellation- Section 4.5 on page 4-82 in the document “Gateways HG 3500 and HG 3575”
Codec Standards - Section 1.3 on page 1-34 in the document “Gateways HG 3500 and HG 3575”

Handling the classmarks for a call

If a call is to be established between Subscriber A and Subscriber B, the classmarks of both subscribers, or of the subscriber and the CO/tie trunk circuit via which the subscriber is reached, are assessed.

Echo cancellation or voice activity detection is only activated if both circuits have set the corresponding classmark.

Connections with announcement devices configured with the AMOs SSC, RCSU or TSCSU are an exception to this rule. Here, the announcement device setting is always adopted.

Table 42. Classmark handling for EC or VAD

EC or VAD		Circuit B		EC or VAD		Announcement Device (RCSU)
EC or VAD		NO	YES	EC or VAD		NO	YES
Circuit A	NO	NO	NO	Circuit A	NO	NO	YES
Circuit A	YES	NO	YES	Circuit A	YES	NO	YES

In the case of codec types, only one type which supports both is selected.

In contrast to version 1, compression is now available for announcement devices and conferences. As far as codec classmarks are concerned, conference trunk circuits are assigned either G711 (default) or G711 & G729OPT when selecting the codec type.

Table 43. Classmark handling for codec type

Circuit A			Circuit B			Codec type used
G711	G729	G729OPT	G711	G729	G729OPT	Codec type used
NO	NO	NO	-	-	-	NONE
NO	NO	YES	-	NO	YES	G.711
NO	YES	-	YES	NO	-	G.711
NO	YES	-	-	NO	YES	G.729
NO	YES	-	-	YES	-	G.729
YES	NO	NO	YES	-	-	G.711
YES	NO	YES	YES	NO	YES	G.711
YES	NO	YES	YES	YES	-	G.729
YES	NO	-	NO	YES	-	G.711
YES	YES	-	YES	NO	YES	G.729
YES	YES	-	YES	YES	-	G.729
YES	-	-	YES	NO	NO	G.711
-	NO	YES	NO	NO	YES	G.711
-	NO	YES	NO	YES	-	G.729
-	YES	-	NO	YES	-	G.729
-	-	-	NO	NO	NO	NONE
- Applies regardless of whether YES or NO is set

Generating the classmarks

The default setting is always EC&G711&G729OPT.

IMPORTANT:

The classmark setting in the CHANGE branches of the AMOs overwrites the setting that existed prior to the AMO call. Therefore, if an additional classmark is to be set, the existing setting must be displayed beforehand and specified again with CHANGE.

If a setting is to be reset to its default value, the value INIT must be specified.

If all classmarks are to be deactivated, the value NONE must be used.

If only some classmarks are to be deactivated, the classmark to be retained must be specified again with CHANGE. All others are automatically deleted.

Examples:

Subscriber:

	Configuration Management > Station > Station Click SEARCH and select the subscriber. Set or delete the required classmarks on the Basic 2 tab under IPDA, IP Connection Features and Save.
	`CHANGE-SDAT:STNO=54321,TYPE=DATA1,CLASSMRK=NONE;` Deactivates all classmarks as required for digital data terminal devices.
	`CHA-SDAT:STNO=54321,TYPE=DATA1,CLASSMRK=EC&G711&G729;` Sets the EC, G711 and G729 classmarks. Use of the G.729 codec is forced if the partner has set G729 or G729OPT.
	`CHANGE-SDAT:STNO=54321,TYPE=DATA1,CLASSMRK=EC&G711&G729&G729OPT&VAD;` Sets the classmarks for EC, G711, G729, G729OPT and VAD (in other words, all).

Attendant console:

	Administration of the attendant console can only be executed in expert mode. Expert Mode > Expert Access > Open ...<IP> with AMO (see AMO command)
	`CHANGE-ACSU:ATNDNO=65432,CLASSMRK=EC&G711;` Sets the EC and G711 classmarks. Calls are always switched without compression and the echo is suppressed.

Announcement devices:

The default setting for AMO SSC and AMO RCSU is always G711&G729OPT&VIAHHS&ML.

The default setting for AMO TSCSU is EC&G711&G729OPT&VIAHHS&ML.

IMPORTANT:

The option of setting G729OPT or even G729 for announcement devices should only be used after careful consideration. G.729 specifies a codec for voice compression. The codec is totally unsuitable for music compression. Music playback is extremely distorted with G.729. In some cases it may be necessary to disable G729OPT particularly if you want to avoid distortions and if circuits have been configured with codec G729.

	Configuration Management > Station > Special Stations Click Search and select the special station (Station Type: EXTANS). Set or delete the required classmarks on the Features tab and Save.
	`ADD-SSC:PEN=1-2-37-10,TYPE=EXTANS,CPCALL=HOLD,CLASSMRK=G711&VIAHHS&ML;` or `CHANGE-RCSU:PEN=1-2-37-5,CLASSMRK=G711&VIAHHS&ML;` Disables G729OPT and sets the G711 classmark. Echo cancellation is not required at announcement devices because the path from the subscriber to the announcement device is not switched.

IMPORTANT:

The classmarks VIAHHS and ML are enabled by default. They may only be disabled in exceptional cases. In the case of CHANGE, do not forget to specify both classmarks if they were previously set.

If VIAHHS is not set, announcements and/or music on hold are no longer distributed via the OpenScape 4000 host system. Instead they are transferred directly from the HG 3575 which hosts the source to all other HG 3575 systems that require the announcement.

If ML is not set, an individual connection is established from the source HG 3575 for each circuit in an access point that requires an announcement or music on hold.

For further information on announcements or music on hold, refer to Section 2.12, “External Music on Hold”.

Conference:

A central configuration switch is used system-wide to set whether or not compressed connections can be connected to conference units.

By default, only uncompressed RTO connections are supported with conference units. In other words, the codec classmarks associated with the conference units are set to G711.

You can use the AMO ZAND to change the setting to G711 & G729OPT.

	Administration of central system data can only be executed in expert mode. Expert Mode > Expert Access > Open ...<IP> with AMO (see AMO command)
	`CHANGE-ZAND:TYPE=ALLDATA3,IPDAVCCF=YES;` This AMO permits compressed connections with the conference unit.

The change becomes effective immediately, that is, the next time an IP connection is connected to a conference unit.

CO/tie trunks:

	Configuration Management > System Data > Trunk > Trunk Click Search and select the circuit. Set or delete the classmarks for IP connections on the Basic Data tab and Save.
	`CHANGE-TACSU:PEN=1-1-91-1,CLASSMRK=EC&G711;` Sets the EC and G711 classmarks. (G729OPT has effectively been deactivated in contrast to the default setting.)
	`CHANGE-TDCSU:PEN=1-1-91-1,CLASSMRK=G711;` Sets the G711 classmark.

IMPORTANT:

If the classmark setting “NONE“ is temporarily required for an outbound call (e.g. for privacy module), this can be done using an access code: AMO WABE: NOEC. This code can only be used as the prefix.

Example

Figure 185. Classmarks

The example in Figure 20 “Classmarks” shows how classmarks are set for different circuits.

The default is G711&G729OPT&EC.

In the central system, there are three exceptions: the fax which does not tolerate signal compression, the compressed tie trunk path and the digital VoiceMail/PhoneMail/Expression server connected. Fax devices can also be configured with the default classmarks if STMI2/4/STMIX/STMIY and NCUI2/4 boards are used exclusively. A sequence of compressions and expansions should be avoided. The selected G711&EC setting in the example ensures that calls from the compressed tie trunk path cannot be compressed a second time. Digital announcement/voice recording devices connected generate absolutely no echo - and save voice in compressed form. Consequently, compression is disabled and EC is deactivated.

The data terminal device on the AP 17 is set to NONE, as it tolerates neither compression nor echo cancellation or attenuation/amplification. When the ISDN service is signaled correctly in the bearer capabilities, transmission is always performed with the NONE classmark, irrespective of the classmark setting.

The AP 35 is connected to the central system via WAN. Bandwidth is therefore a precious commodity and voice compression should always be used if possible. The setting G711&G729&EC for telephones and the CO line ensures that calls with telephone subscribers in the central system and AP 17 are compressed, as are calls from telephones in the central system or AP 17 via the local CO line in AP 35.

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