Technical data

How Call Addresses Are Processed
Dialogic
®
Diva
®
SIPcontrol
TM
Software 1.8 Reference Guide page 50
CHAPTER 7
How Call Addresses Are Processed
The call addresses provided by the caller may be modified at different stages of the call processing within the
Dialogic
®
Diva
®
SIPcontrol
TM
Software. The reason for multiple manipulation is that it allows for modifying the
address where it is needed, which means that more complex environments can be configured with less effort,
since data does not need to be entered redundantly at different places. It also makes it easier to "team" SIP
peers or PSTN interfaces with different settings.
The Diva SIPcontrol software converts addresses automatically, without any intervention from the user. This
means that the Diva SIPcontrol software adds or removes a special prefix to a number with a known number
type, e.g. "+" for international numbers, when converting between a number and an address. See Common
formats: on page 54 for a list of prefixes.
Note: Number type flags from digital networks, e.g., ISDN or SS7 are converted into special prefixes on the
SIP side. International numbers get a "+" prefix, national numbers get an "N" prefix, and subscriber numbers
get an "S" prefix.
The automatic conversions are done for calling numbers, called numbers, and redirected numbers.
Possible scenarios
• At a PSTN interface, a line access digit must be prepended in order to call to the public network, while another
PSTN interface is directly connected and does not need an access digit.
Solution: Add a regular expression to outbound address map of the first interface.
• All calls to a number beginning with "9" shall be routed to one specific SIP peer while removing this digit.
Solution: Manipulate the called number in the route.This way the SIP peer may also receive calls to other
numbers (via other routes) without having to deal with different number formats.
• SIP peer "A" needs the dialed numbers to be formatted in E.164 format, while SIP peer "B", which is in
load-balancing or fail-over partnership with "A", needs it in an extension-only format.
Solution: Define different number formats in the SIP peer settings.
• SIP peer "A" is located at a different location than SIP peer "B", e.g., London and Stuttgart. Therefore, both
need different location settings regarding country and area codes, etc.
Solution: Create different dialplans and assign each dialplan to one SIP peer.
How addresses are manipulated
Note: Each step is optional.
1. Save the inbound call addresses as "A".
2. Apply the "address map inbound" of the endpoint assigned to the call setup request to "A", resulting in "B".
3. To check the first route: apply the number format settings of the route together with the dialplan of the
source endpoint to the call addresses "B", resulting in "C".
4. Check the route as described in the route processing section (5) against addresses "C". If the route does
not match, discard the changes and try the next route with "B" again.
5. If the route matches, apply the route address map to the addresses "C", resulting in "D".
6. After selecting one of the destinations of the route, normalize the addresses "D" using the dialplan and
number format of the destination endpoint, resulting in addresses "E".
7. Apply the outbound address map of the destination endpoint to "E", giving the effective call addresses "F"
sent to the destination.
8. If the call to the selected destination endpoint fails and if there are other endpoints in a fail-over configuration,
start with step 6 again with the respective settings of the next endpoint.