# Notification of Employment, Call Waiting
1. Go to the [System file customization](https://docs.mikopbx.com/mikopbx/english/manual/system/custom-files) section
System file customization menu
2. Proceed to editing the "**modules.conf**" file
modules.conf file
3. Add the following code to the end of the file:
```php
load => func_extstate.so
```
Code for modules.conf
4. Go to editing the file "**extensions.conf**"
extensions.conf file
5. Add the following code to the end of the file:
```php
[internal-users-custom]
exten => _X!,1,Progress()
same => n,ExecIf($["${EXTENSION_STATE(${EXTEN})@internal-hints}" = "INUSE" || "${EXTENSION_STATE(${EXTEN}@internal-hints)}" = "RINGINUSE"]?Playback(beep))
same => n,ExecIf($["${EXTENSION_STATE(${EXTEN})@internal-hints}" = "INUSE" || "${EXTENSION_STATE(${EXTEN}@internal-hints)}" = "RINGINUSE"]?Set(TRANSFER_OPTIONS=${TRANSFER_OPTIONS}m))
same => n,return
```
6. In the extension card, in the "**Advanced Settings**" - "**Extra Options**" field, set the value
```php
[endpoint]
device_state_busy_at = 3
```
If the employee is busy, a **beep** file (a short beep) will be played to the caller, then music will be played instead of beeps until the employee answers the call
{% hint style="warning" %}
**device\_state\_busy\_at** is the number of conversations at which the employee should be considered "busy", in this case the "**Routing Settings**" rules described in the employee card will start working.
{% endhint %}
If the problem solution does not work correctly, change the code in **extensions.conf** to:
```php
[internal-users-custom]
exten => _X!,1,Progress()
same => n,NoOp(${EXTEN})
same => n,NoOp(${DEVICE_STATE(PJSIP/${EXTEN})})
same => n,ExecIf($["${DEVICE_STATE(PJSIP/${EXTEN})}" = "INUSE" || "${DEVICE_STATE(PJSIP/${EXTEN})}" = "RINGINUSE"]?Background(nomer&zanjat))
same => n,ExecIf($["${DEVICE_STATE(PJSIP/${EXTEN})}" = "INUSE" || "${DEVICE_STATE(PJSIP/${EXTEN})}" = "RINGINUSE"]?Set(TRANSFER_OPTIONS=${TRANSFER_OPTIONS}m(callwaiting)))
same => n,return
```
