7. Advanced Subscriber Configuration

7.1. Access Control for SIP Calls
7.1.1. Block Lists
7.1.1.1. Block Modes
7.1.1.2. Block Lists
7.1.1.3. Block Anonymous Numbers
7.1.2. NCOS Levels
7.1.2.1. Creating NCOS Levels
7.1.2.2. Creating Rules per NCOS Level
7.1.2.3. Assigning NCOS Levels to Subscribers/Domains
7.1.3. IP Address Restriction
7.2. Call Forwarding and Call Hunting
7.2.1. Setting a simple Call Forward
7.2.2. Advanced Call Hunting
7.2.2.1. Configuring Destination Sets
7.2.2.2. Configuring Time Sets

The sip:provider CE provides a large amount of subscriber features in order to offer compelling VoIP services to end customers, and also to cover as many deployment scenarios as possible. In this chapter, we will go over the features and describe their behavior and their use cases.

7.1. Access Control for SIP Calls

There are two different methods to provide fine-grained call admission control to both subscribers and admins. One is Block Lists, where you can define which numbers or patterns can be called from a subscriber to outbound direction and which numbers or patterns are allowed to call a subscriber in inbound direction. The other is NCOS Levels, where the admin predefines rules for outbound calls, which are grouped in certain levels. The user can then just choose the level, or the admin can restrict a user to a certain level. Also sip:provider CE offers some options to restrict the IP addresses that subscriber is allowed to use the service from. The following chapters will discuss these features in detail.

7.1.1. Block Lists

Block Lists provide a way to control which users/numbers are able to call or to be called, based on a subscriber level, and can be found in the Call Blockings section of the subscriber preferences.

Subscriber Block Lists

Block Lists are separated into Administrative Block Lists (adm_block_*) and Subscriber Block Lists (block_*). They both have the same behavior, but Administrative Block Lists take higher precedence. Administrative Block Lists are only accessible by the system administrator and can thus be used to override any Subscriber Block Lists, e.g. to block certain destinations. The following break-down of the various block features apply to both types of lists.

7.1.1.1. Block Modes

Block lists can either be whitelists or blacklists and are controlled by the User Preferences block_in_mode, block_outmode__ and their administrative counterparts.

  • The blacklist mode (option is not checked tells the system to allow anything except the entries in the list. This mode is used if you want to just block certain numbers and allow all the rest.
  • The whitelist mode indicates to reject anything except the entries in the list. This is used if you want to enforce a strict policy and allow only selected destinations or sources.

You can change a list mode from one to the other at any time.

7.1.1.2. Block Lists

The list contents are controlled by the User Preferences block_in_list, block_out_list and their administrative counterparts. Click on the Edit button in the Preferences view to define the list entries.

In block list entries, you can provide shell patterns like * and []. The behavior of the list is controlled by the block_xxx_mode feature (so they are either allowed or rejected). In our example above we have block_out_mode set to blacklist, so all calls to US numbers and to the Austrian number +431234567 are going to be rejected.

Outgoing Block List

Click the Close icon once you’re done editing your list.

7.1.1.3. Block Anonymous Numbers

For incoming call, the User Preference block_in_clir and adm_block_in_clir controls whether or not to reject incoming calls with number supression (either "[Aa]nonymous" in the display- or user-part of the From-URI or a header Privacy: id is set). This flag is independent from the Block Mode.

7.1.2. NCOS Levels

NCOS Levels provide predefined lists of allowed or denied destinations for outbound calls of local subscribers. Compared to Block Lists, they are much easier to manage, because they are defined on a global scope, and the individual levels can then be assigned to each subscriber. Again there is the distinction for user- and administrative-levels.

NCOS levels can either be whitelists or blacklists.

  • The blacklist mode indicates to allow everything except the entries in this level. This mode is used if you want to just block certain destinations and allow all the rest.
  • The whitelist mode indicates to reject anything except the entries in this level. This is used if you want to enforce a strict policy and allow only selected destinations.
7.1.2.1. Creating NCOS Levels

To create an NCOS Level, go to SettingsNCOS Levels and press the Create NCOS Level button.

NCOS Levels

Select a reseller, enter a name, select the mode and add a description, then click the Save button.

Create NCOS Levels

7.1.2.2. Creating Rules per NCOS Level

To define the rules within the newly created NCOS Level, click on the Patterns button of the level.

Enter NCOS Pattern View

In the Number Patterns view you can create multiple patterns to define your level, one after the other. Click on the Create Pattern Entry Button on top and fill out the form.

Create NCOS Pattern

In this example, we block (since the mode of the level is blacklist) all numbers starting with 439. Click the Save button to save the entry in the level.

The option include local area code in list for a blacklist means that calls within the area code of the subscribers are denied, and for whitelist that they are allowed, respectively. For example if a subscriber has country-code 43 and area-code 1, then selecting this checkbox would result in an implicit entry ^431.

7.1.2.3. Assigning NCOS Levels to Subscribers/Domains

Once you’ve defined your NCOS Levels, you can assign them to local subscribers. To do so, navigate to SettingsSubscribers, search for the subscriber you want to edit, press the Details button and go to the Preferences View. There, press the Edit button on either the ncos or admncos setting in the Call Blockings__ section.

Assign NCOS Level

You can assign the NCOS level to all subscribers within a particular domain. To do so, navigate to SettingsDomains, select the domain you want to edit and click Preferences. There, press the Edit button on either ncos or admin_ncos in the Call Blockings section.

Note: if both domain and subscriber have same NCOS preference set (either ncos or adm_ncos, or both) the subscriber’s preference is used. This is done so that you can override the domain-global setting on the subscriber level.

7.1.3. IP Address Restriction

The sip:provider CE provides subscriber preference allowed_ips to restrict the IP addresses that subscriber is allowed to use the service from. If the REGISTER or INVITE request comes from an IP address that is not in the allowed list, the sip:provider CE will reject it with a 403 message. Also a voice message can be played when the call attempt is rejected (if configured).

By default, allowed_ips is an empty list which means that subscriber is not restricted. If you want to configure a restriction, navigate to SettingsSubscribers, search for the subscriber you want to edit, press Details and then Preferences and press Edit for the allowed_ips preference in the Access Restrictions section.

Edit Subscriber Allowed IP Addresses

Press the Edit button to the right of empty drop-down list.

You can enter multiple allowed IP addresses or IP address ranges one after another. Click the Add button to save each entry in the list. Click the Delete button if you want to remove some entry.

7.2. Call Forwarding and Call Hunting

The sip:provider CE provides the capabilities for normal call forwarding (deflecting a call for a local subscriber to another party immediately or based on events like the called party being busy or doesn’t answer the phone for a certain number of seconds) and serial call hunting (sequentially executing a group of deflection targets until one of them succeeds). Targets can be stacked, which means if a target is also a local subscriber, it can have another call forward or hunt group which is executed accordingly.

Call Forwards and Call Hunting Groups can either be executed unconditionally or based on a Time Set Definition, so you can define deflections based on time period definitions (e.g. Monday to Friday 8am to 4pm etc).

7.2.1. Setting a simple Call Forward

Go to your Subscriber Preferences and click Edit on the Call Forward Type you want to set (e.g. Call Forward Unconditional.

Create Simple Call Forward

If you select URI/Number in the Destinatio field, you also have to set a URI/Number. The timeout defines for how long this destination should be tried to ring.

7.2.2. Advanced Call Hunting

If you want multiple destinations to be executed one after the other, you need to change into the Advanced View when editing your call forward. There, you can select multiple Destination Set/Time Set pairs to be executed.

A Destination Set is a list of destinations to be executed one after another.

A Time Set is a time definition when to execute this Destination Set.

7.2.2.1. Configuring Destination Sets

Click on Manage Destination Sets to see a list of available sets. The quickset_cfu has ben implicitely created during our creation of a simple call forward. You can edit it to add more destinations, or you can create a new destination set.

Create CF Destination Set

When you close the Destination Set Overview, you can now assign your new set in addition or instead of the quickset_cfu set.

Assign CF Destination Sets

Press Save to store your settings.

7.2.2.2. Configuring Time Sets

Click on Manage Time Sets in the advanced call-forward menu to see a list of available time sets. By default there are none, so you have to create one.

Create CF Time Set

You need to provide a Name, and a list of Periods where this set is active. If you only set the top setting of a date field (like the Year setting in our example above), then it’s valid for just this setting (like the full year of 2013 in our case). If you provide the bottom setting as well, it defines a period (like our Month setting, which means from beginning of April to end of September).

[Important]

the period is a through definition, so it covers the full range. If you define an Hour definition 8-16, then this means from 08:00 to 16:59:59 (unless you filter the Minutes down to something else).

If you close the Time Sets management, you can assign your new time set to the call forwards you’re configuring.