| Issue: Getting a fast busy on all outbound calls.
Root Cause: The carrier in this instance is AT&T. They have different ISDN switch types in each individual Central Office (CO). Therefore, customer premise PRI's could be connected to 5ESS or DMS switches in the local CO. Each ISDN switch type has slightly different capabilities. 5ESS switches do not support calling name being sent on outbound calls over the PRI (only calling number is supported), whereas DMS does support calling names.
Resolution: The fix was to disable calling names being sent out the PRI trunks. This can be done at a global level or per trunk level.
The Global setting is located:
Under VoIP, GW and IP to IP, Digital Gateway, Digital Gateway Parameters, Remove Calling Name. Remove Calling Name should be set to "Enabled".
The Trunk setting is located:
Under VoIP, PSTN, Trunk Settings. Remove Calling Name should be set to "Enabled".
Some other configurable parameters to note are the following:
- Under VoIP, GW and IP to IP, Manipulations, Dest IP to Tel. Make sure that you are only sending 10 digits to the PSTN in North America. The carrier is only able to perform CLID lookups using the Area Code/NPA/NXX number format. So you need to have a Dest IP to Tel manipulation to strip any preceding digits such as "1" or "+".
- Also, make sure that you have "E.164 Public / National" NPI and TON respectfully. Make sure that "Allowed" is also configured for the rule.
- Under VoIP, GW and IP to IP, Manipulations, Source Number IP to Tel. Make sure that you are only sending 10 digits to the PSTN in North America. The carrier is only able to perform CLID lookups using the Area Code/NPA/NXX number format. So you need to have a Source Number IP to Tel manipulation to strip any preceding digits such as "1" or "+".
- Also, make sure that you have "E.164 Public / National" NPI and TON respectfully. Make sure that "Allowed" is also configured for the rule.
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