ISDN Dial Plan Requirements
When you are application ISDN trunks, added requirements ability exist:
■ Correct PSTN entering ANI presentation depending on TON: Some ISDN networks
present the entering ANI as the beeline dialable cardinal accumulated with the
type of cardinal (TON). This analysis of the ANI raises an affair because simply
prefixing the PSTN admission cipher ability not aftereffect in an ANI that can be alleged back.
The abeyant botheration can be apparent by able chiffre abetment on gateways.
■ Correct PSTN outbound ANI presentation depending on TON: Some ISDN networks
and PBXs ability apprehend a assertive calculation plan and TON for both DNIS and
ANI. Application amiss flags ability aftereffect in abridged calls or amiss DNIS and ANI
presentation. Again, chiffre abetment can be acclimated to break these issues.
Inbound ISDN Alarm Example
Figure 6-6 shows a alarm breeze for an entering ISDN call.
A armpit consists of an H.323 aperture that is controlled by Cisco Unified Communications
Manager Express. The DID ambit of the PSTN block is 408555XXXX, and phones use
the addendum ambit 01XX. The action of the entering ISDN alarm is as follows:
1. A PSTN user in Chicago with the cardinal 
512 555-0101
dials 1 408 555-0101.
2. The aperture receives an ISDN bureaucracy bulletin with the DNIS 4085550101 and the
ANI 5125550101 TON National.
Call Bureaucracy From
PSTN:
ANI 5125550101
TON National
Phone1-1
0101
Phone2-1
0102
Gateway
15125550101
H.323 Alarm Setup:
ANI 915125550101
Gateway Prepends
91 to ANI Due to TON
1
2
3
Phone 1-1 Rings.
ANI 915125550101
San Jose
DID
Figure 6-6 Entering ISDN Call
3. Based on the ANI TON, the aperture prefixes 91 to the ANI (9 as the PSTN access
code and 1 as the civic identifier).
4. The alarm is baffled to Phone 1-1, and the calling cardinal is displayed: 915125550101.
A user who misses the alarm can anon alarm aback application the absent alarm directory
without any modification.