Reference:Administration/Gateway/Routes

The most important task of the gateway is call routing. It determines which calls are accepted and where they are switched to.

Call routing is carried out by the gateway's gatekeeper and is controlled by routes (for voice). For each call direction, a route must be defined. If a call passes several gateways, a relevant route must be defined in each one. A route defines a permitted path for a call, from the interface where the call arrives, to the interface from which the call departs. Calls from different interfaces are often handled in the same way. Therefore, calls from several ISDN interfaces (for example, TEL1 and TEL2) or from several VoIP interfaces (GW1-12), for example, can be permitted.

Call switching also often depends on the call number dialled. For this, the validity of routes for calls with particular destination numbers must be defined by means of a map entry. Each map entry defines that calls from the source interfaces specified in the route beginning with the combination of digits specified in the map entry can be connected to the destination interface defined in the route.

All defined routes are displayed row by row in the routing table. For each individual call, the routing table is searched from top to bottom for a suitable map entry. If it is not possible to switch the call to the identified interface, then the routing table is searched for the next map entry that meets the specified conditions. If a map entry was found, the current call is switched to the destination interface of the map entry defined. If no suitable map entry was found, the call is invalid and is not put through.

From - To

The routing table is structured as follows:

• From: The source interface from which a call is to be accepted. It may be an ISDN interface (TEL, BRI, PRI, etc.) or a VoIP interface (GW1-12).
• To: The destination interface to which a call is to be switched. It may be an ISDN interface (TEL, BRI, PRI, etc.) or a VoIP interface (GW1-12).
• CGPN Maps: The CGPN (Calling Party Number) map is used for modifying the calling number. It allows the extension to be suppressed for outgoing calls, for example, but also the entire map entry can be made dependent on the calling number.

To create a new routing entry, you must click the Insert Route below button. A popup page opens, on which the route setting can be made.

This popup page also contains the specification of the map entries. Clicking the Add Map above/below buttons opens the same popup page and adds a map entry at the relevant place. This popup page is structured as follows:

• Description: The descriptive name for the route.
• Source interface: Here, you select the ISDN or VoIP interface that is to apply as the source for the relevant route. It is also possible to select several sources. The source interfaces available in principle are: RT, RS, TEL, BRI, PRI, PPP, TEST, TONE, HTTP, SIP and GW.
• Number In: To make the routing decision dependent on a map entry, you must enter the calling number here. If no number is specified here, the map entry is valid for all calls.
  There are additional variants of call number manipulation available:
  If a route is to apply to a particular number and all of the digits that are subsequently dialled are to be ignored, the specified call number must be followed by the "!" operator.
  Some devices require the "#" operator as the signalling character for the end of a call. For this, the Add # check box can be checked (see description further down in the text).
  With the "?" operator, it is also possible to replace a variable unknown and known number of characters by a particular one. For example, "???" replace with 1 gives, say for "1234" -> "14", or "0???" replace with 1 gives, say for "01234" -> "14", since the known digit 0 is likewise replaced.
  With the "." operator, a particular number of characters can be replaced. For example, "..." replace with "123" gives, say for "321" -> "123".
• Number Out: Here, you enter the route’s call number to be replaced, if desired. If the call number is to be adopted unchanged, the same call number as in Number In must be specified here.
  

 Note: If the calling number was manipulated, the Verify CGPN check box must not be checked,
since the checking of the calling number would fail, making the map entry ineffective.

• Destination interface: Here, you select the interface that is to apply as the destination for the relevant route. The destination interfaces available in principle are: RT, RS, TEL, BRI, PRI, PPP, TEST, TONE, HTTP, SIP, GW, MAP and DISC.
• Name Out: If the H.323 call name is to be changed, the new call name can be entered here.
• Cause (DISC): If the DISC destination interface was selected, a so-called disconnection cause (see Appendix C "ISDN Errorcodes") can be additionally specified, to obtain appropriate output on the terminal.

For every route definition, advanced settings can be made:

• Add UUI: If manufacturer-specific data is to be transmitted in the signalling channel, for example, the URL for an announcement, then this URL (http://192.168.0.1/webdav) can be specified here.
• Final Route: A checked check box simulates the end of the routes. If further routes are to follow, they are ignored.
• Final Map: A checked check box simulates the end of the map entries. If further map entries are available, all further map entries are ignored.
• Exclude from Auto CGPN: If the Automatic CGPN Mapping check box was checked in chapter "Administration/Gateway/General", the relevant route can be excluded from the automatic correction of all calling numbers by checking this check box.
• Verify CGPN: The routing decision is normally made on the basis of the routes themselves and the map entries defined in the routes. With a checked check box, the routing decision is made on the basis of the CGPN maps. This means that first the calling number is checked and, only if the calling number matches, is the routing table further processed and call switching, for example, takes place.
  Since this only applies to the verification and restriction of particular numbers, no manipulation of the call number takes place here. In this way, access to a chargeable trunk line, for example, can be restricted to certain extensions (selective direct outward dialling).
  If the Automatic CGPN Mapping check box was checked in chapter "Administration/Gateway/General", the check is applied to the number already corrected.
• Interworking (QSIG): A checked check box enables translation of H.323 or SIP to QSIG. Here, no translation from QSIG to H.323 or SIP takes place, rather, the transmission is transparent (is used where PBXs of the same kind are linked via VoIP).
• Force Enblock: A checked check box enforces enbloc dialling. This means that if a map entry applies, all subsequently dialled digits are collected until more than four seconds have passed since the last digit was dialled.
• Add #: A checked check box transmits the hash character (#) to mark the end of a call number. This is only required for terminals that do not recognise the end of the call number (such as Cisco terminals, for example).
• Disable Echo Canceller: A checked check box suppresses echo cancellation for the relevant map entry. This is normally only necessary if the connection used as the voice connection is not to perform echo cancellation, as is the case with modems, for example.
• Call Counter max: If there is insufficient bandwidth available, a name can be entered in the Call Counter field, and the maximum number of calls permitted for the relevant route can be entered in the max field.

Clicking the name of a route (for example, TEL1:exchange) filters the display of the routes by the set interface. Clicking the name of the route a second time again shows the routes that are not associated. If, for example, several routes have been created for the TEL1 interface, then clicking one of the TEL1 interfaces hides all other routes that do not have TEL1 selected as the source or destination interface.

The adjacent arrow button (-->) can be used to edit routes.

CGPN Maps

It is also often necessary to define routes depending on the calling number. Just as maps are added to routes, so-called CGPN maps must be added to the maps for this purpose. This not only allows calling numbers to be manipulated in order to suppress the extension for outgoing calls, for example, but also the entire map to be made dependent on the calling number. The arrow button (-->) in the CGPN Maps column can be used to define and edit such maps.

• Number In: The calling number. The CGPN map is valid if the inbound E.164 call number matches the call number or dial prefix set here.
• Name In: The calling name. The CGPN map is valid if the inbound H.323 call name matches the name set here.
• Number Out: Here, you enter the call number or dial prefix to be replaced for the switching.