Troubleshooting guide

4-6
Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 4 Troubleshooting with Call Flows
Understanding MGCP
Each event can be qualified by a requested action or by a list of actions. The actions, when specified, are
encoded as a list of keywords, enclosed in parentheses and separated by commas. The codes for these
events are:
• N (Notify immediately, with the accumulated list of observed events)
• A (Accumulate)
• D (treat according to Digit map)
• S (Swap audio)
• I (Ignore)
When no action is specified, the default action is to notify the event. This means that, for example, ft and
ft(N) are equivalent. Events not listed are ignored.
The swap audio action can be used when a gateway handles more than one active connection on an
endpoint. This is the case for three-way calling, call waiting, and possibly other features. In order to
avoid the round-trip to the call agent when only changing the connection attached to the audio functions
of the endpoint, the notification request can map an event (usually hook-flash) to a local function swap
audio, which selects the next connection in a round robin fashion. If there is only one connection, this
action is effectively no operation.
The digit-map action can be specified only for the digits, letters and timers.
The requested list is encoded on a single line, with event or action groups separated by commas.
Examples:
R: hu(N), hf(S,N)
R: hu(N), [0-9#T](D)
Signal Requests (S)
The Signal Requests parameter contains the set of actions that the gateway is asked to perform on the
endpoint. Each signal is identified by a code, as shown in Table 4-5.
Continuity tone co
Continuity detected (as a result of a continuity test) cv
On-hook transition hu
Off-hook transition hd
Flash hook hf
Digit collection Individual digits (e.g. “#”), timers (“T”), or
ranges (e.g. “[0-9]” or “[0-9*#T]”)
Table 4-4 Requested Events (continued)
Event Code
Table 4-5 Signal Requests
Signal Code
Ringing rg
Distinctive ringing (8 variants numbered 0-7) r0, r1, r2, r3, r4, r5, r6, or r7
Ring back tone rt