Overlap Signaling (Sending) - SIP to SS7

There are two methods supported by the IMG to interwork Called Party Number digits between SIP & SS7. One method labeled Enbloc requires that all the Destination address information be included in the IAM or INVITE. The other method is Overlap.  The IMG currently supports Overlap Receiving where the destination address is contained in an IAM and SAM sequence of messages or a series of INVITES, each containing one or more destination address digits. The received digits are buffered until the configured minimum number of digits is received at which point the outgoing call is made with the destination address Enbloc. Refer to the Overlap Signaling (Receiving) topic.

This feature will allow Overlap Sending of destination address digits. In this case each received IAM and subsequent SAM message will be interworked to a series of INVITES each containing all the destination address digits received to that point, similarly when the SIP interface receives a series of INVITES, each containing additional destination address digits to the previous one, these will be mapped into an IAM, SAM sequence with each message containing only the 'new' digits of the latest INVITE.

 

Call Flow Diagram

The Diagram below assumes that the Minimum Number of Digits field in the Channel Group pane is set to 1

cf_ss7_sip_sip_ss7_overlapsignaling.png

Call Trace Example

Click on the SIP to SS7 Call Trace link for Call Trace Information

Click on the SS7 to SIP Call Trace link for Call Trace Information

 

Configuration

Overlap sending is configured under the Channel Group Object. The IMG supports interworking the Overlap signaling messages from SIP to SS7 and from SS7 to SIP, therefore Overlap sending is configured in both the SIP and SS7 Channel Groups. When configuring Overlap, both the incoming and outgoing channel groups must have Overlap Enabled. The configuration below explains receiving overlap signaling on an SS7 channel group and transmitting out a SIP channel group.

 

Initial Configuration

The procedure below explains how to configure SIP Privacy on the IMG. Before configuring, the IMG must have an initial configuration created on it. Below are links to the initial configuration needed.

Configure these initial objects before proceeding to the procedure below.

 

Create SS7 Channel Group

  1. Right click on Routing Configuration and selecting New Channel Groups. The Channel Groups object is a container object for individual channel groups to be created under. No configuration is needed. Refer to the Channel Groups topic for more information on this object.

  2. Right click on Channel Groups object and select New Channel Group. Enter a name to identify the channel group being created.

  3. Select SS7 from the drop down menu of the Signaling Type field.

  4. In the Overlap Enable field select Enabled from drop down menu. This will enable Overlap and opens the next four fields for editing. See screen capture below.

sc_overlap_channelgroup_ss7_sp11.png

Termination Digit - Select from drop down menu the characters #, *, and 0-9

Minimum # of Digits - Minimum number of digits received to be able to route call.

Inter SAM Timeout - Maximum amount of time between each Subsequent Address Method (SAM). (Default = 1500 milliseconds or 1.5 seconds)

Total Overlap Timeout - Max time allowed for a call to be setup. (Default = 18000 milliseconds or 18 seconds)

Refer to the Channel Group topic for more information on configuring the channel group object.

  1. Once the SS7 Channel group is created, the SIP channel group needs to be created. Right click on Routing Configuration and select New Channel Group.

sc_overlap_channelgroup_sip_sp11.png

Termination Digit - Not Used. SIP does not use termination digits.

Minimum # of Digits - Minimum number of digits received to be able to route call.

Inter SAM Timeout - Maximum amount of time between each Subsequent Address Method (SAM ). (Default = 4000 milliseconds or 4 seconds)

Total Overlap Timeout - Not Used

  1. Overlap is enabled on both SS7 Channel Group and SIP Channel Group.

Additional Information:

 

Related Topics:

Channel Group