Configuring busy tone detection
This section describes how to configure busy tone detection for FXO voice subscriber lines.
Configuring busy tone detection parameters for the FXO voice subscriber line
The actual specifications of busy tones might differ from the configured parameters. If this is the case, busy tones cannot be recognized, resulting in failed or false on-hook.
To configure the busy tone detection parameters for the FXO voice subscriber line:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | System-view | N/A |
2. Enter voice view. | voice-setup | N/A |
3. Configure busy tone detection parameters. | vi-card busy-tone-detect { auto index line-number | custom area-number index argu f1 f2 p1 p2 p3 p4 p5 p6 p7 } | Optional. The system can record four busy tones which are identified by the index argument. |
4. Configure the type of busy tone. | area { custom | europe | north-america } | Optional. By default, the busy tone compliant with the European standard is used. Once you execute this command, the configuration will be applied to all FXO voice cards on the device. |
5. Quit voice view. | quit | N/A |
6. Enter FXO voice subscriber line view. | subscriber-line line-number | N/A |
7. Configure the number of busy tone periods for detection. | busytone-t-th time-threshold | Optional. The default is 2. You can increase the number of busy tone detection periods by using the busytone-t-th command to improve the busy tone detection accuracy. This reduces the likelihood of false on-hook, but increases the likelihood of failed on-hook. |
![[NOTE: ]](images/note.png) | NOTE: Before you configure the number of busy tone detection periods, test the new value repeatedly to make sure that the new value does not cause failed or false on-hook. | |
Enabling the busy tone sending
If the PBX fails to play a busy tone to a digital telephone, enable the FXO interface to send a busy tone to the PBX, which will transparently send the busy tone to the digital telephone.
To enable the busy tone sending:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter FXO voice subscriber line view. | subscriber-line line-number | N/A |
3. Enable the busy tone sending. | send-busytone { enable | time seconds } | Optional. Disabled by default. The time option appears only after the send-busytone enable command is executed. |
Enabling silence detection-based automatic on-hook
Silence detection-based automatic on-hook prevents the situations where the resource of the FXO interface cannot be released owing to busy tone detection failure when the busy tone parameters provided by the connected PBX are special.
When the signal values of two successive sampling points are less than the silence threshold, the system considers that the line goes into the silent state. If the line stays in the silent state longer than the silence duration for automatic on-hook, the system will automatically disconnect the call.
Do not enable silence detection-based automatic on-hook unless you are sure it is necessary. Improper configuration of this function can lead to false on-hook.
To enable silence detection-based automatic on-hook:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter FXO voice subscriber line view. | subscriber-line line-number | N/A |
3. Enable silence detection-based automatic on-hook. | silence-th-span threshold time-length | Optional. By default, the silence threshold is 3 and the silence duration for automatic on-hook is 7200 seconds (2 hours). |
| NOTE: It is a good practice to test multiple sets of parameters and choose the set of parameters that can quickly release the FXO voice subscriber line after on-hook and does not cause false on-hook. | |
Configuring the duration before a forced on-hook
In some countries, PBXs do not play busy tones, or the busy tones played only last for a short period of time. When noise is present on a transmission link, the silence-th-span command might fail to release the FXO interface after on-hook. In this case, use the hookoff-time command to solve the problem.
To configure the duration before a forced on-hook:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter FXO voice subscriber line view. | subscriber-line line-number | N/A |
3. Configure the duration before a forced on-hook. | hookoff-time time | Optional. Forced on-hook is disabled by default. The configuration will take effect on all interfaces of a card after this command is executed. |
![[IMPORTANT: ]](images/important.png) | IMPORTANT: Once forced on-hook is enabled, calls will be automatically disconnected when the duration expires, even if the conversation is going on. | |
Configuring the delay time before an on-hook
Usually, after the FXO interface detects a busy tone, the system automatically disconnects the call and immediately removes the connection. When an FXO subscriber line is used as the VoIP access port can cooperate with an IP phone, because the IP phone does not play any prompt tone to the IP phone user, it is easily for the IP phone user to ignore the busy tone and considers that the line failure occurs when the FXO subscriber line detects the busy tone and removes the connection quickly.
With the delay time before an on-hook configured, when the FXO subscriber line detects a busy tone, it waits for a period of time, and then disconnects a call and removes the connection. In this case, the busy tone is first sent to the FXO interface and then sent to the IP phone, and the IP phone user will easily confirm the busy tone information before the connection is removed.
To configure the delay time before an on-hook for the FXO voice subscriber line:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter FXO voice subscriber line view. | subscriber-line line-number | N/A |
3. Configure the delay time before an on-hook for the FXO voice subscriber line. | busytone-hookon timer seconds | Optional. The default delay time is 0 seconds. |