Multimedia Call Routing

The H.223 and H.245 protocols are used to establish multimedia calls between endpoints over circuit switched networks. These protocols come into play after successful call completion between the multimedia endpoints. The initial SS7/ISDN call setup messages contain an octet that indicate that the call will utilize H.223/H.245. Feature F-5230 ‘Multimedia Call Routing' supports routing calls based on the presence of this specific octet. Thus with this feature, routing is configured using the new routing criteria type 'Multimedia Call'.

The feature will make use of the existing IMG routing capability.  The analysis in this document will identify the relevant bit values and their locations within initial call setup messages that identify a call as a multimedia call.  It will describe the routing criteria that the GCEMS needs to set in the route entries when this feature is selected in the configuration. The route action rule portion in the route entry remains the same as for the other existing route options. That is, once the multimedia call is identified and matched with the route entry, the action of routing is the same as for other configurable call criteria. Note that having committed the ‘Multimedia Call’ criteria a total of six route table entries are sent to the switch.

 

H.223/H.245 Indication

For SS7, the ‘User Information Layer 1 Protocol’ parameter forms part of the ‘User Service Information’ IE which, when set as ‘Recommendation H.223 & H.245’ along with ‘Layer 1 Identity’ and extension bit gives the octet a hex value of 0xa6. This parameter may appear in different locations within the information element due to the presence of other octets.  The ‘User Information Layer 1 Protocol’ parameter may also be presented in the ‘Low Layer Compatibility’ IE as part of the ‘Access Transport’ IE in which, again the ‘User Information Layer 1 Protocol’ parameter may be presented in different locations within the information element due to the presence of other octets and other information elements.

For ISDN the  ‘User Information Layer 1 Protocol’ parameter forms part of the ‘Bearer Capability’ IE or part of the ‘Low Layer Compatibility’ IE.  Again, the ‘User Information Layer 1 Protocol’ parameter may be presented in different locations within the Information Elements due to the presence of other octets.

The IMG will scan the incoming initial message for the ‘Recommendation H.223 & H.245’ value of the ‘User Information Layer 1 Protocol’ where ever it is located and will route the call on this criteria

 

User Information Layer 1 protocol:

Bits 5 4 3 2 1

Description

00001

ITU-T standardized rate adaptation V.110, I.460 and X.30.This implies the presence of octet 5a and optionally octets 5b, 5c and 5d as defined below.

00010

Recommendation G.711 [10]] u-law.

00011

Recommendation G.711 A-law.

00100

Recommendation G.721 [11] 32 kbit/s ADPCM and Recommendation I.460.

00101

Recommendation H.221 and H.242

00110

Recommendation H.223 [92] and H.245 [93].

00111

Non-ITU-T standardized rate adaption. This implies the presence of octet 5a and, optionally, octet 5b, 5c and 5d. The use of this codepoint indicates that the user rate specified in octet 5a is defined by the user. Additionally, octets 5b, 5c and 5c, if present, are defined in accordance with the user specified rate adaption.

01000

ITU-T standardized rate adaption V.120 [9]. This implies the presence of octets 5a and 5b as defined below, and optionally octets 5c and 5d.

01001

ITU-T standardized rate adaption X.31 [14] HDLC flag stuffing.

 

The value highlighted in above table will be set in the routing criteria in the route table entries.

 

Below is table displaying the format of the User Service Information/Bearer Capability IE.

 

8

7

6

5

4

3

2

1

Octet 1

ext 1

Coding Standard

 Information Transfer Capability

Octet 2

ext 1

Transfer Mode

Information Transfer Rate

Octet 2a

ext 1

Rate Multiplier

Octet 3

ext 0/1

Layer 1 Identity

User Information Layer 1 Protocol

 

Below is table displaying the format of the Low Layer Compatibility IE.

 

8

7

6

5

4

3

2

1

Octet 3

ext 0/1

Coding Standard

 Information Transfer Capability

Octet 3a

ext 1

Neg. Ind

Spare

Octet 4

ext 1

Transfer Mode

Information Transfer Rate

Octet 4.1

ext 1

Rate Multiplier

Octet 5

ext 0/1

Layer 1 Identity

User Information Layer 1 Protocol

 

 

 

 

The format of this IE can change based on values in each of the octets. For example, octet 2a is required if octet 2 indicates multirate(64 kbit/s base rate); otherwise it shall not be present. For this reason there can be multiple locations for the User Information Layer 1 protocol parameter coming from ISDN/SS7. For the IMG to route on a Multimedia call, it must be able to match on the required parameters to specify the H.223/H.245. The possible combinations are displayed below.

 

 

Option 1: Routing Criteria for User Information Layer 1 Protocol in User Service Info IE with no Rate Multiplier octet

Criteria

Octet 1

Octet 2

Octet 3

Description

Criteria Digits

00000000

00000000

00100110

Coding Standard

Information Transfer Capability

Transfer Mode - (Circuit Mode)

Information Transfer Rate - (other than Multirate 64 kbit/s base rate)

Layer 1 Identity

User Information Layer 1 Protocol -  (Recommendations H.223 and H.245)

 

 

 

Option 2: Routing Criteria for User Information Layer 1 Protocol in Low Layer Compatibility IE with Negotiation Indicator/Spare and Rate Multiplier octets

Criteria

Octet 3

Octet 3a

Octet 4

Octet 4.1

Octet 5

Description

Criteria Digits

00000000

00000000

00011000

00000000

00100110

Ext (0), Coding Standard, Information Tx Capability

Negotiation Indicator, Spare

Transfer Mode - (Circuit Mode)

Information Transfer Rate - (Multirate 64 kbit/s base rate)

Rate Multiplier  (don't care about value)

Layer 1 Identity

User Information Layer 1 Protocol -  (Recommendations H.223 and H.245)

 

 

 

Option 3: Routing Criteria for User Information Layer 1 Protocol in Low Layer Compatibility IE with Negotiation Indicator/Spare octet and with no Rate Multiplier octet

Criteria

Octet 3

Octet 3a

Octet 4

Octet 5

Description

Criteria Digits

00000000

00000000

00000000

00100110

Ext (0), Coding Standard, Information Transfer Capability

Negotiation Indicator

Spare

Transfer Mode - (Circuit Mode)

Information Transfer Rate - ( other than Multirate 64 kbit/s base rate)

Layer 1 Identity

User Information Layer 1 Protocol -  (Recommendations H.223 and H.245)

 

 

 

Option 4: Routing Criteria for User Information Layer 1 Protocol in Low Layer Compatibility IE with no Negotiation Indicator/Spare octet and with Rate Multiplier octet

Criteria

Octet 3

Octet 4

Octet 4.1

Octet 5

Description

Criteria Digits

10000000

00011000

00000000

00100110

Ext (1), Coding Standard, Information Transfer Capability

Transfer Mode - (Circuit Mode)

Information Transfer Rate - (Multirate 64 kbit/s base rate)

Rate Multiplier

Layer 1 Identity

User Information Layer 1 Protocol -  (Recommendations H.223 and H.245)

 

 

 

Option 5: Routing Criteria for User Information Layer 1 Protocol in Low Layer Compatibility IE with no Negotiation Indicator/Spare octet and no Rate Multiplier octet.

Criteria

Octet 3

Octet 4

Octet 5

Description

Criteria Digits

10000000

00000000

00100110

Ext (1), Coding Standard, Information Transfer Capability

Transfer Mode - (Circuit Mode)

Information Transfer Rate - (other than Multirate 64 kbit/s base rate)

Layer 1 Identity

User Information Layer 1 Protocol -  (Recommendations H.223 and H.245)

 

 

Configuration:

Below are instructions on how to configure the IMG to route calls dependant on whether call is categorized as 'multimedia'. Verify the following entities are configured before proceeding:

The procedure below will start from the Routing Configuration Pane within ClientView. The following configuration example will demonstrate the configuration needed to accept a call coming from SS7 and route them based on the routing criteria 'Multimedia Calls'.  

 

Create SS7 Channel Group:

The first step would be to create an SS7 Channel Group. This Channel group would be configured as an SS7 Channel group. In this feature, the SS7 Channel Group would receive an incoming call from PSTN and route the call to a Route Table which would then send call to a Route Table Entry.

Channel Group Initial Configuration:

  1. Right Click on IMG EMS and select New Routing Configuration. A Routing Configuration Pane will appear. See Routing Configuration for more information on this object.

  2. Right Click on Routing Configuration and select New Channel Groups. A Channel groups container object is created. This object will allow multiple channel groups to be created beneath it. See Channel Groups for more information on this object.

Create SS7 Channel Group:

  1. Right Click on the Channel Groups Object and select New Channel Group. A Channel Group Object will appear. Enter a name for this channel group and set the 'Signaling Type' to 'SS7'. The Incoming Channel Group in this example will be an SS7 Channel Group and be named ChGrp_SS7. See Channel Group for more information on configuring a channel group.

Create H.323 Channel Group:

  1. Right Click on the Channel Groups Object and select New Channel Group. A Channel Group Object will appear. Enter a name for this channel group and set the 'Signaling Type' to 'SS7'. The Incoming Channel Group in this example will be an H323 Channel Group and be named ChGrp_H323.

 

Create Route Tables and then Route Table Entries:

The routing for this feature will now be accomplished. The next few steps will configure the objects needed to route the call.

Create Route Table and Route Table Entry:

  1. Right Click on Routing Configuration and select New Routing Tables. The Routing Tables object created is a container object which will allow multiple individual Routing Tables to be created beneath it. See Route Tables for more information.

  2. Right Click on Routing Tables and select New Route Table. A Route Table object will get created. Enter a name for this Route Table. In this example the name will be Route Table 1. Click in the 'Routing Criteria Order field and an arrange items box will appear. Select 'Multimedia Call' and move it to the uppermost position. See screen capture below. This will give Multimedia calls the highest priority. See Creating a Route Table for more information on configuring the Route Table Object.

    sc_f5230_arrange_items.png

  3. Create a Route Entry under the Route Table by right clicking on Route Table and select Add Entry. A Route Entry screen will appear. Click in the 'Routing Criteria Type' field and a drop down menu appears. Select 'Multimedia Call' from the list.

    sc_f5230_routeentry_select.png
     

  4. In the Outgoing Channel Group field of the Route Entry object select which channel group to send call out on. In this example, the H.323 Channel group was selected. See below

    sc_f5230_routeentry_chgrp_select.png
     

  5. Finish configuring the Route Entry. See Route Entry for more information on this object.

Configure Channel Group to access Route Table configured:

  1. Once the Route Table and Route Entry are configured, go back to the incoming Channel Group created. Select the Route Table configured above from the drop down menu in the 'Route Table' field. See Below.

    sc_f5230_rtetable_select.png
     

  2. By selecting the Route Table, the rejected call with the Cause Code configured will be sent out this Channel Group.

 

Flow of above Configuration:

After configuring the Route Call to a Cause Code feature above the following bulleted list explains what happens once a call comes into the IMG and IMG rejects call with Cause Code configured.

 

 

Additional Information: