Technical information
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Ordering DID Service
Ordering DID Service
To order DID Service in the United States:
Determine what your DID requirements are and how many simultaneous calls you are going to support.
How many phone numbers will you need to reserve? The minimum block of phone numbers offered by most
major regional DID service providers is 20.
How many simultaneous inbound calls do you want to support? This will determine the number of DID trunk
lines you need to order. You have the option of picking a block of numbers that will be serviced by a specific
number of DID trunk lines. These DID trunk lines will work in a rollover process whereby if someone dials one
of the numbers in your block and the first trunk line is busy, it will roll over to the next trunk line and so on until
it finds an idle trunk line. This is automatically supported by your DID service provider and does not require
that you purchase any additional equipment.
Before you place your DID service order with your service provider, you need to know how to request the options
described in:
2-Wire DID interface
DTMF signaling
Wink start
Number of DTMF digits to outpoll
2-Wire DID interface
This specifies the physical connection from the DID service provider and your local terminating point.
DTMF signaling
This specifies the type of signaling that your local equipment is expecting. Choices are rotary, pulse and multi-
frequency.
Wink start
This is a signal from the DID service provider to the DID interface unit that tells it a DID call is ready to be received.
Number of DTMF digits to outpoll
This specifies the number of DTMF digits that you want to receive prior to accepting the call and is used by the fax
software to identify the number being called and resolve a name or department from the DID table. Although you can
specify how many digits you want to receive, the maximum number is 7. The actual number will be based on your
particular environment.
Contact your service provider and specify that you are ordering a DID trunk line.
If your current PBX phone switch does not have provisions for supporting DID service, you need to contact a DID
interface equipment manufacturer to purchase an interface unit. DID trunk lines are dedicated lines from the service
provider that require a special interface at the customer's site. The interface equipment is available in models that