Method for Pacing Call Retry Attempts on an Integrated Services Digital Network
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2005-Mar-30
Freeman, TS: AUTHOR [+2]
A method for pacing the retry (and subsequent retries) of a previously failed Integrated Services Digital Network (ISDN) call to a predefined time interval is disclosed.
Method for Pacing Call Retry Attempts on an Integrated
A method for
pacing the retry (and subsequent retries) of a
previously failed Integrated Services Digital Network (ISDN) call to
a predefined time interval is disclosed.
imposed by certain ISDN networks state that a
device must not automatically attempt more than a certain number of
circuit switched calls within a specified time duration to the same
destination for the case that these calls are failing (a CONNECT
message is not received).
described herein is based upon keeping a list of
the most recently used Called Party Numbers (destination device's
phone number) for circuit switched calls. When a request is made to
place an outgoing a call, but the destination phone number is on the
list, the call is not sent. List entries are removed after a fixed
time duration. This makes it again possible for a call to be made to
that phone number. More detailed description follows:
to make an outgoing call - When the upper layer
requests to make a call, the Layer 3 Call Control Layer first
determines that the content of the request is valid and that the
network resources (B-channel) exist to place the call (this is
unchanged from the pre-existing implementation). Next it is
determined whether the destination phone number for this call is
already on the list. Three possibilities exist:
1. The number is on the list - In this case, no further action is
taken on this call request and the upper layer is informed
the call has failed. It is the responsibility of the upper
to retry the call at a later time. The network resources
available for call attempts to other destinations.
2. The number is not on the list but the list is full. - This is
the case of handling the exception situation of the list being
full. This case is treated identically to the previous case.
That is the call is failed and the upper layer must retry the
call at a later point in time. If this was the first time
call was attempted to this number then it is unfortunate that