ZyXEL Communications IES-1248-51A, User Manual

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Chapter 45 VoIP
IES-1248-51V User’s Guide
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Figure 149 H.248/MEGACO Call Procedure Example
The user of phone A wants to call the user of phone B. The following table shows
the series of actions necessary to set up the network and make the call
(TransactionRequests and TransactionReplies are not shown).
Note: This table illustrates the actions taken in setting up, conducting, and tearing
down a call. However, some of the actions may take place simultaneously (for
instance, when the MGC instructs MG1 and MG2 to switch to Listening mode).
Also, the commands necessary to perform some series of actions may be sent
in the same Transaction.
Table 111 H.248/MEGACO Call Procedure Example
DIRECTION ACTION COMMAND
MG1 --> MGC MG1 registers with MGC and reports its
capabilities to the MGC. ServiceChange
MG2 --> MGC MG2 registers with MGC and reports its
capabilities to the MGC. ServiceChange
MGC --> MG1 MGC sets MG1 to listening mode. Modify
MGC --> MG2 MGC sets MG2 to listening mode. Modify
Phone A --> MG1 User of phone A lifts the receiver off-hook. MG1
detects off-hook. N/A
MG1 --> MGC MG1 reports phone A off-hook to MGC. Notify
MGC --> MG1 MGC instructs MG1 to play the relevant dial tone
to Phone A. Modify
Phone A --> MG1 User of phone A dials phone B’s number. N/A
MG1 --> MGC MG1 informs MGC of the dialed number. MGC
examines dialed number, which correlates with
phone connected to MG2. Notify
MGC --> MG1 MGC creates RTP Termination in MG1 (in the
same Context as Phone A’s existing analog
Termination). Add
MGC --> MG2 MGC creates RTP Termination in MG2 (in the
same Context as Phone B’s analog Termination). Add
ANALOG
ANALOG
IP Network
PHONE A
PHONE B
MG1
MG2
MGC