Preventing Calls from Being Transferred Through a Trunk and the IVR
This section describes how to configure call attributes for a call prefix, call-out right for call transfer through a trunk, maximum number length for the IVR, and call-out right for call transfer through the IVR to prevent inter-office users from making outgoing calls through the PBX or IVR.
Context
- 0: intra-office call
- 1: local call
- 2: national toll call
- 3: international toll call
- 4: local survival call
The 214 control point enables or disables automatic determination and call restriction functions, and it does not affect the call restriction functions when national and international toll call prefixes are configured.
If the 214 control point is configured for the system to restrict calls not according to the calling parties' call-out rights, toll fraud may occur. In this case, the national and international toll call prefixes must be configured to prevent toll fraud.
Mapping between the call prefix attribute and call-out rights for calls transferred over a trunk and the IVR:
Assume that the right for the inter-office call prefix between PBX1 and PBX2 is 1.
- If a PSTN user calls a user on PBX2 through the trunk of PBX1, the call-out right of the trunk must contain the call-out right (right 1) of the inter-office call prefix.
- If a PSTN user dials the IVR through PBX1 and calls a user on PBX2, the IVR and trunk call-out rights of PBX1 must contain the call-out right (right 1) of the inter-office call prefix.
Configuring the Call-Out Right for Calling Number Discrimination
For the calling party whose incoming calls are made over a trunk, the default call-out right is the same as that for calls transferred over a trunk. If the call-out right for calling number discrimination is configured on the PBX, the call-out of the calling party is that configured for calling number discrimination. To prevent users from calling inter-office users after calls are connected over a trunk, configure the call-out right for calling number discrimination.
- Specific users need to have special rights.
- Calling numbers other than the specific ones (7000–7999) are not allowed to make outgoing calls.
<Huawei> system-view [Huawei] voice [Huawei-voice] caller-change 0 [Huawei-voice-caller-change-0] callerprefix 7* [Huawei-voice-caller-change-0] outgoing-right inter enable [Huawei-voice-caller-change-0] caller no-change [Huawei-voice-caller-change-0] called no-change [Huawei-voice-caller-change-0] save
Configuring Call Attributes for the Call Prefix
Assume that the prefixes 9, 90, and 900 indicate the local calls, national toll calls, and international toll calls. Call prefix 9 is used as an example. For call prefixes 90 and 900, set attribute values to 2 and 3. For details, see Configuring a Call Prefix.
<Huawei> system-view [Huawei] voice [Huawei-voice] callprefix 9 [Huawei-voice-callprefix-9] prefix 9 [Huawei-voice-callprefix-9] call-type category basic-service attribute 1 [Huawei-voice-callprefix-9] digit-length 1 32 [Huawei-voice-callprefix-9] save
Configuring the Call-Out Right for Calls Transferred Through a Trunk
Call-out rights are classified into inter, local, ddd, idd, all. You can configure multiple call-out rights simultaneously. The default call-out rights for calls transferred through a trunk are inter and local. To enable the PBX not to forward incoming calls over a trunk, configure inter. If a user makes a call over a trunk and wants to call a local user, configure inter and local. If a user wants to make national or international toll calls, configure ddd or idd. For details on how to configure call-out rights, see Configuring Call Limiting Over a Trunk.
It is recommended that outgoing-right of the trunk between PBX1 and PBX2 be set to inter&local and outgoing-right of the trunk between the PBXs and the PSTN be set to inter.
<Huawei> system-view [Huawei] voice [Huawei-voice] trunk-group sippra [Huawei-voice-trunkgroup-sippra] outgoing-right local enable [Huawei-voice-trunkgroup-sippra] callroute 1 [Huawei-voice-trunkgroup-sippra] save
If a trunk has local right or more rights, a user can make a call over this trunk and calls inter-office users, which may cause a call fraud.
Configuring the Maximum Number Length for the IVR
Assume that a 4-digit extension number is used. Set the second-dialing number length to 4 so that an inter-office user only needs to dial the IVR and extension number to call the intra-office user. If the second-dialing number length is larger than or equal to the inter-office number length, when inter-office call conditions are met, an inter-office user can dial the IVR and another inter-office user. As a result, a call fraud occurs. To prevent users from dialing the IVR and inter-office user's number, set the second-dialing number length to the intra-office number length. For details, see IVR Configuration.
Configuring the IVR Call-Out Right
Call-out rights are classified into inter, local, ddd, idd, all. You can configure multiple call-out rights simultaneously. The default call-out right is inter. By default, after a user dials the IVR, the user cannot call an inter-office user. If a user wants to dial the IVR and make outgoing calls, configure the call-out right.
<Huawei> system-view [Huawei] voice [Huawei-voice] callprefix 888 [Huawei-voice-callprefix-888] vuoutgoingright local enable [Huawei-voice-callprefix-888] save
When the IVR has local right or more rights, a user can dial the IVR, hear the second-stage dialing tone, and dial the inter-office user's number, which may cause a call fraud.