SETUP-CALL-ROUTING-Channel-Groups

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Channel Groups

Channel Groups displays all the channels available and lets you group channels together by signaling type. You can also modify or delete existing groups. To create a channel group, click Create Channel Group. This displays the Channel Group Configuration page.

  • Enter a name for the channel group.
  • Specify the device type.
  • Select the channels to add to the group.
  • Enter the Callback Extension and the Default Fax Extension for the channel. Voice calls that do not match any Incoming Call rules or routes are sent to the Callback Extension. If you have fax installed, Fax calls that do not match any Incoming Call Routes are sent to the Default Fax Extension.

NOTE: Unless you are an advanced user, do not change any of the other settings.

  • When you are done, click Save Channel Group to create the group.

WARNING: Switchvox restarts after you create a new channel. Any current calls are dropped, and any agents logged into queues are logged out.

Device Types

Device Type describes the type of line that is connected to the PBX through this device. The following options are available:

FXO and FXS. Foreign Exchange Office (FXO) and Foreign Exchange Service (FXS) device types refer to the type of interface on the telephone equipment: an FXO interface receives power (battery) and receives ring signals; and an FXS interface provides power (battery) and generates ring signals. FXO devices can only communicate with FXS devices and vice versa. Each FXO and FXS type listed in the dropdown has an associated signaling type: kewlstart, loopstart, or groundstart. The signaling type is the “language” the interface uses to communicate to the devices connected to it. Some devices have their signaling type preset and cannot be changed (for example, analog cards). Some devices can have their signaling type changed to match the devices they are connected to.

NOTE: You cannot have both FXS and FXO channels in the same group. However, you can create more than one group per signaling type.

FXO (Foreign Exchange Office) with Kewlstart signaling. Select this option if you are connecting normal analog phone lines from the phone company into your PBX. This option can also be used with certain T1 lines or T1 channel banks in rare instances.

FXO (Foreign Exchange Office) with Loopstart signaling. Do not use this option. Use FXO with Kewlstart instead. Kewlstart is fully compatible with Loopstart, and will detect hangups on most lines which the Loopstart option does not do.

FXO (Foreign Exchange Office) with Groundstart signaling. Groundstart is an alternate type of signalling used with analog phone lines from the phone company. Groundstart phone lines are slightly unusual, so double-check with your provider before selecting this option.

FXS (Foreign Exchange Station) with Kewlstart signaling. Select this option if you are connecting a normal analog handset to an FXS port of an analog card.

FXS (Foreign Exchange Station) with Loopstart signaling. It is recommended to use the Kewlstart option instead of Loopstart.

FXS (Foreign Exchange Station) with Groundstart signaling. Select this option if you are connecting a groundstart FXS device, such as another analog PBX, to the FXS port of an analog card.

PRI. The Data channel is a single channel used for call control on T1/E1 PRI connections. It is usually on channel 24 for T1, and 16 for E1 connections. The Bearer channels carry the audio for T1/E1 PRI calls. Full PRIs use all channels except for the D channel. Partial PRIs use a subset for the Bearer channels.

PRI T1/E1 D (Data) Channel. The Data channel is a single channel used for call control on T1/E1 PRI connections. It is usually on channel 24 for T1, and 16 for E1 connections.

PRI T1/E1 B (Bearer) Channel. The Bearer channels carry the audio for T1/E1 PRI calls. Full PRIs use all channels except for the D channel. Partial PRIs use a subset for the Bearer channels.

BRI. The Data channel is the third channel on every BRI that controls signaling. The Bearer channels are the first two channels on a BRI that actually pass calls.

BRI D (Data) Channel. The Data channel is the third channel on every BRI that controls signaling.

BRI B (Bearer) Channel. B channels are the first two channels on a BRI that actually pass calls.

E&M Signaling. The E&M (Ear & Mouth) Signaling device type is a different type of T1 signaling used by some telephone companies. E&M signalling describes certain older T1 lines. Select this option if you have an E&M or E&M-wink circuit, sometimes referred to as a Supertrunk.

Callback Extension

This is the extension to ring when a voice call comes in over this provider or channel. Callback extensions can be any extension type (your receptionist’s phone, an IVR, etc.).

Default Fax Extension

This is the extension to ring when a call comes in over this provider or channel, and is identified as a fax. (Switchvox only identifies T.38 faxes over SIP providers. A fax coming in over an IAX provider or a channel, or a fax using a different standard may not be identified as a fax.)

Advanced Options

It is unusual to change the Advanced Options, so they are hidden. If you find that you need to change an Advanced Option, click Show Advanced Options.

Aggressive Echo Cancellation. This option enables aggressive echo suppression in the Analog echo canceller. This is done by making the line half-duplex, or by muting the party that is not actively speaking. While this does eliminate echo, it might cause other problems such as not being able to interrupt a speaking party, or clipping on the leading and trailing edge of speech. Setting this option to run for the first 5 seconds of a call is an effective way to eliminate echo that eventually trains out. Otherwise, it Is best to keep this option disabled.

Apply Noise Reduction Filter. This option applies a filter on calls to reduce analog line noise. This can improve quality on very old analog lines in rural areas. Before enabling this option, it's best to call your provider to see if they can improve the signal quality or strength from their end, as this option only masks over the noise.

Automatic Gain Correction. Enabling this will automatically adjust the received volume of calls to a standard volume level. This should be the first thing to try if inbound calls are too quiet, specifically on analog lines.

Automatically determine call progress. Do not enable this option unless explicitly instructed to. Enabling this option in the wrong environment will result in dropped calls.

Battery Debounce. This option is extremely advanced and only used in very rare circumstances in certain countries. This option controls how Switchvox looks for a hangup signal on Kewlstart lines. In Kewlstart signalling, hangup is sent by a voltage drop in the analog lines for a certain period of time. The Battery Debounce controls how long Switchvox waits until concluding that it has received a hangup signal. If set too low, line noise or lightning or regular speech can be interpreted as a hangup. If set too high, correct hangup signals will not be received. The default value for this setting is chosen to be the perfect balance. Do not change it unless you have physically measured the duration of a battery drop for your country's telephone lines.

Battery Threshold. This option is extremely advanced and only used in very rare circumstances in certain countries. This option controls how Switchvox looks for a hangup signal on Kewlstart lines. In Kewlstart signalling, hangup is sent by a voltage drop in the analog lines for a certain period of time. The Battery Threshold controls how low the voltage must go before being considered dropped. The default setting for this option will work in most countries. Do not change it unless you've physically measured the duration of a battery drop for your country's telephone lines.

Caller ID Signaling. Caller-ID is sent over analog lines differently in different countries. This option controls which method to read the caller-ID. The options are Bell (for countries like the USA), v23 (United Kingdom), and DTMF (Sweden). When changing this value, also make sure to adjust the Caller ID Start value to correspond to your country.

Caller ID Start. Different countries send caller-ID at different times. This option instructs Switchvox when to look for the caller-ID signal. The choices are ring (for countries like the USA), or polarity (for countries like the United Kingdom).

Detect busy signal. This option will listen for the busy signal to trigger a hangup. It is strongly recommended to leave this option disabled and have your telco send a true disconnect signal. This option may be enabled in countries that do not have disconnect supervision. If you are in the USA, UK, Australia, or Canada, you should not need to enable this option. If this option is enabled, it is advised to increase the Busy Count setting to as many tones as possible to avoid false-positives that may result in dropped calls.

Echo Cancel. This option enables or disables echo cancellation on the system. We strongly recommend setting this option to Yes. Setting this option to No will disable both software echo cancellation, and any onboard hardware echo canceller on the given card.

Echo Cancel when bridging TDM channels. This option controls echo cancellation for calls that enter Switchvox on one hardware channel, and exits Switchvox on another hardware channel. IE: this affects calls that do not touch any VoIP Providers or SIP handsets. Calls of this nature do not normally need echo cancellation, so it is safe to leave this option to the default of No.

NOTE: This setting does not apply to calls to normal SIP handsets.

Echo Canceller Tail Length. This controls how long the canceller should listen for echo to return. It is best to use the smallest value possible. For analog lines, echo is usually in the 64 or 128 range. For T1 lines, 128 or greater.

Echo Canceller Type. Different echo canceller types may perform better in certain situations.

Analog. A good general-purpose echo canceller that works best on analog lines, or on T1 lines with shorter echo tails. This is the default echo canceller, and is a good place to start.

T1. This echo canceller works best on T1 lines with long echo tails, but may also outperform other types in certain analog environments.

HPEC (High Performance Echo Cancellation), Digium software. To use this option, you must have an HPEC license installed.

Acoustic. This experimental echo canceller is tuned for acoustic echo. While good on paper, this method of cancellation hasn't worked very well in practice.

Fax Buffer Policy

Set the Fax Buffer Policy for this Channel Group. To turn this option off, select Disabled. The default is Half. This option lets you set a buffer policy to prevent fax failures on high latency systems. See the related option "Number of Fax Buffers." You must install a fax license and the fax software to make faxing available. For details, see the “Digium Addon Products” article.

Fax Detection

Set the Fax Detection for this Channel Group.

Both. Detect incoming and outgoing faxes, and behave appropriately.

No. Do not detect incoming or outgoing faxes.

Incoming. Detect incoming faxes and behave appropriately. Do not detect outgoing faxes.

Outgoing. Detect outgoing faxes and behave appropriately. Do not detect incoming faxes.

NOTE: You must install a fax license and the fax software to make faxing available.  For details, see the “Digium Addon Products” article.

Fax Error Correction Mode

Error Correction Mode (ECM). The default is to leave this feature enabled.

Hang up on Polarity Switch

Some countries, most notably Australia, signal remote hangup by switching the polarity of the lines. This is sometimes called ROIC (Reverse On Idle Condition). Only enable this option if you have confirmed with your telco that hangups are signalled with polarity reversal.

Hardware Echo Cancellation

This option enables the hardware echo cancellation module on BRI cards.

Hide caller ID. Enabling this option will disable sending caller-id for this channel group.

Maximum transfer rate for fax transmissions.  Maximum transfer rate used during fax rate negotiation. The default maximum transfer rate is 14400. 

Minimum transfer rate for fax transmissions. Minimum transfer rate used during fax rate negotiation. The default minimum transfer rate is 2400.

Network Specific Facility Code

This option is rarely used. If you are unsure of what to do, leave it set to None.

NSF, or Network Specific Facility codes are special codes that are sent in PRI facility messages and are used to signal additional data to your telephone company. Do not change this setting unless your telephone company explicitly stated that they require a specific NSF value.

Number of Fax Buffers

Set the number of fax buffers. The default is 12. This option lets you set a buffer policy to prevent fax failures on high latency systems. See the related option “Fax Buffer Policy.” You must install a fax license and the fax software to make faxing available. For details, see the “Digium Addon Products” article..

Overlap dial

Overlap dialing sends each digit pressed as it's entered, instead of sending the entire number all at once. It is safe to leave this option disabled.

Pause Before Dialing

This option adds a slight delay to allow the off-hook signal to propagate to the telephone company before sending down DTMF digits. This should not need to be changed.

PRI Dialplan

This controls how outbound calls are sent over the PRI. Check with your PRI provider to confirm which method they prefer.

PRI Reset Interval

The default value for this option, 3600, is usually correct. This controls how often the PRI B channels are reset when they are unused. For the vast majority of PRI lines, this has no effect on the PRI and is purely done just to be safe. However, some PRIs in countries such as India may have problems with being reset. In that case, you may want to enter a value of never.

PRI Switch Type

Your PRI provider should be able to provide you with the preferred PRI Switchtype. The most common option is National ISDN 2, sometimes referred to as NI2.

Relax DTMF Recognition

Enabling this option will make the DTMF interpreter much more permissive. If you are having trouble receiving DTMF key presses in IVRs with calls over a channel group, enabling this option may help. Unfortunately, it also may result in many more false positives, or double keypresses. In cases where poor line quality is hampering DTMF detection, it is highly recommended to improve the line quality first before enabling this option.

Ring Debounce

This option is only used in very rare circumstances in certain countries. This option controls how long Switchvox waits before confirming a ring on analog lines. The value is in 1/8000ths of a second, and the default is 1024. Larger numbers cause Switchvox to wait longer, potentially making it harder to receive false-positives or ghost calls. Smaller numbers cause Switchvox to be more sensitive to rings.

RX Gain

We recommend enabling ***Automatic Gain Correction *** before altering this option. This controls the volume of audio received from this channel group. For example, if incoming callers are too quiet or too loud, this option can change the volume. Values are in decibels, and can be positive or negative to make calls louder or quieter respectively. This is usually only needed on analog lines (not T1 lines) to compensate for signal loss in the wires. Normal values range in the -15 to 15, and it's recommended to start low, and increment the gains by a factor of 2 until they reach the correct volume (e.g., 2, 4, 6, 8...).

Secondary Device Type

This option should almost always be set to PRI (Primary Rate ISDN) CPE Side. Consult your T1 provider before selecting an alternate option.

Train echo canceller at beginning of calls

This option sends a pulse at the beginning of a call in the attempt to pre-train the echo canceller. This can improve situations with echo at the beginning of a call.

TX Gain

This controls the volume of audio sent from this channel group. It is recommended to not increase this value, although lowering it to -3 may improve call quality and/or echo. If in doubt, leaving this setting at the default of 0.0 is recommended.

Use Caller ID

Enabling this option will enable receiving (and sending) caller-id. It is almost always recommended to leave this set to Yes. The one situation where it may be prefereable to disable caller-id is when using analog lines in a country (such as the USA) that sends the caller-ID between the first and second ring. In order to receive caller-ID on analog lines, Switchvox has to wait until the second ring before answering. If caller-ID is disabled, Switchvox will answer inbound calls immediately, without waiting for the caller-ID.

Wait Duration

This forces the system to wait the specified number of seconds before answering the call, allowing time to receive all of the call data before answering the call. The default is 1. Most likely you do not need to change the default.

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