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LX give you the ability to analyze and debug SIP and ISDN call flows.


Adding and Viewing Call Flows

Searching For A Call

You can either search for a call in the Call tab, or you could use the Ctrl+S search feature.

Regex Called/Calling #

Use regular expressions to search for called/calling number patters. For example, if one call leg used 4-digit numbering plan and another uses E.164 numbering plan, the destination number in one of the call legs could be 2474 and +15105742474 in the other call leg. Therefore, a regular expression of (.2474) will find the calls that contain the 2474 pattern in the called and/or calling numbers.

Called #

Use exact match for called number.

Calling #

Use exact match for calling number.

Call-ID / Machine-ID

Use SIP Call-ID or ISDN Machine-ID


Use this to find all SIP requests or response. This is useful when you are searching for a specific response, for example 504 Server Time-out.

Viewing A Call Flow

When LX parses the log, it shows the calls placed in the Calls tab in the Lower Display Pane.

To view the call flow for a call:

  1. Double click anywhere in the row for the call you want to analyze.
    A Call Flow dialog opens with the contents of the Call Flow.

  2. Click on a message in the Call Flow Pane to view its contents in the Message Contents Pane.
    In this example, the INVITE message in the call flow has been selected and its contents are displayed in the Message Contents Pane on the right side of the dialog.

Viewing multiple calls in the Call Flow Ladder:

Since one call usually has multiple call legs, most often it help to see the messages (ISDN and SIP) for all call legs in a sequential order. There are two ways to do this.

  1. Select multiple calls in the Calls tab and hit Enter. All messages associated with these two calls will be displayed in a new dialog. This is the recommended and most commonly used way to analyze calls.
  1. Use the Add Call-ID to Call Flow feature allows you to add multiple call legs to the call flow pane.

To add more Call IDs:

  1. With the Call Flow dialog open, press CRTL+S to open the Add Call-ID to Call FlowDialog.

  2. Select the Enabled check box.

  3. Select the Call IDs you wish to add.
  4. Click OK
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