Method of establishing a data link between a pair of terminals as well as a terminal which is suitable for implementing this method

A method of establishing a data link between a first terminal, which is capable of communicating in accordance with a number of different data communication standards, and a plurality of further terminals which are each capable of communicating in accordance with a single data communication standard, whilst indicators (profile indicators) are extended to the dial numbers of the further terminals in the first terminal these indicators showing according to which data communication standard a specific further terminal is operating. If such an indicator is found with the telephone number when a link to a further terminal is established, the first terminal is automatically reprogrammed for subsequent operation in accordance with the data communication standard of the further terminal. The method can also be implemented when a terminal which is capable of communicating in accordance with a single data communication standard calls the first terminal, provided that the calling terminal transmits its call accompanied by its telephone number. Also a terminal for implementing the method.

The invention relates to a method of establishing a data link between a 
first terminal, which is capable of communicating in accordance with a 
number of different data communication standards, and a plurality of 
further terminals which are each capable of communicating in accordance 
with a single data communication standard. 
For the purpose of data communication between a pair of terminals 
integrated in an ISDN system (Integrated Services Digital Network) a large 
number of different standards, such as for example V110, X30 and ECMA102 
have been known to date. There are also terminals which still operate with 
data communication standards that are the predecessors of the present 
standards. Also the present standards are constantly modified so that 
incompatibility may develop in many different ways amongst the methods 
used to communicate between; terminals. Even if two terminals operate in 
accordance with the same version of the same standard, they can still be 
incompatible, because for example the one terminal use a specific option 
defined within the standard, such as flow control or network independent 
clocking in ECMA102 or V110, while the other terminal does not use this 
option. 
There are ISDN terminals which are capable of operating according to 
different data communication standards by reprogramming. There are also 
ISDN terminals which operate according to a first data communication 
standard for links inside their own systems and, when an external link is 
to be established, are reprogrammed so as to operate according to a 
different data communication standard; but this reprogramming is a 
time-consuming operation requiring programming skill from the user. 
It is an object of the invention to provide a method according to which a 
programmable terminal is capable of communicating with a plurality of 
terminals operating according to different data communication standards, 
without the user needing to carry out a labour-intensive reprogramming of 
his own terminal. 
The method according to the invention is characterized in that, in the 
first terminal, indicators are attributed to the telephone numbers of at 
least a group of further terminals, these indicators showing according to 
what data communication standard a specific further terminal is operating, 
and in that the first terminal is automatically reprogrammed so as to 
operate according to the data communication standard of the further 
terminal if such an indicator is found with the telephone number, when a 
link to a further terminal is established. 
According to another aspect of the invention, if the first terminal is 
called by a terminal whose telephone number and associated indicator are 
known to the first terminal, whilst the calling terminal or the calling 
exchange also transmits its own telephone number with the call, the first 
terminal is automatically reprogrammed in accordance with the indicator 
associated to the received telephone number, so as to enable communication 
with the calling terminal. 
This is specifically advantageous in a case when an older type of terminal, 
which may be an internal or an external terminal, calls a more recent 
reprogrammable type. 
With the invention it is assumed that if the reprogrammable terminal is the 
called terminal, the user of this terminal will know according to which 
data communication standard the called terminal is operating, because it 
is needless to observe that it is impossible to enter the right indicator 
with respect to the data communication standard to be implemented to be 
called profile indicator hereinafter, as an extension to the telephone 
number of this terminal. Once this profile indicator has been entered, the 
same or subsequent users need no longer know which data communication 
standard this specific terminal uses, because this information will then 
already be known in the calling terminal itself. For the further aspect of 
the invention it is likewise assumed that a calling terminal, or the 
exchange to which this terminal is coupled, as is customary with ISDN, 
transmits, to the called terminal identification, data from which at least 
the dial number of this terminal can be derived. 
The invention likewise provides a terminal, and more specifically a 
telephone set, which is suitable for implementing the said method, this 
terminal including a reprogrammable control unit for enabling the terminal 
to operate according to a number of different data communication standards 
and a memory for storing the telephone numbers of a plurality of further 
terminals, this memory including memory locations for storing indicators 
as extensions to at least a group of telephone numbers and a table in 
which the data for reprogramming the control unit which belong to each 
indicator are stored.

In the block diagram of FIG. 1 the blocks have the following meanings: 
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Block 
number Legends Description 
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2 INC. CALL? Check whether it is a matter of an 
incoming call or an outgoing call 
3 SELECT Select the telephone number of the 
called subscriber by means of a 
preselection key or figure keys. 
4 PROFILE? Check whether a profile indicator 
is stored with the selected tele- 
phone number 
5 SEARCH . Search the table for the terminal 
parameters belonging to this profile 
indicator 
6 FOUND? Check whether the terminal para- 
meters are found 
7 REPROGRAM Automatic reprogramming of the 
terminal 
8 CONNECTION Establish the selected link 
9 DATA EXCH. Data exchange is taking place 
10 CLEAR Reprogramming is cancelled and 
the original terminal parameters 
are entered again 
12 DNR. REC? Check whether a telephone number 
is received from the calling 
subscriber 
13 SEARCH DNR Search the memory of the called 
terminal for this telephone number 
14 FOUND? Check whether this telephone num- 
ber is found 
15 PROFILE? Check whether a profile indicator 
is stored with the found telephone 
number 
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When the terminal is activated there is a first check to find whether it is 
a matter of an incoming or an outgoing call (block 2). In the case of an 
outgoing call the telephone number of the desired subscriber is to be 
selected by means of either the figure keys, or a preselection key (block 
3) previously reserved for this number. Subsequently, in the memory of the 
terminal it is checked whether a profile indicator is stored together with 
the telephone number (block 4). If this is the case, a table available in 
the terminal memory is searched for reprogramming parameters belonging to 
this profile indicator (block 5) and if they are found indeed, the 
terminal is reprogrammed in accordance with these parameters (block 7). 
Then, the link with the selected subscriber is established and the data 
are exchanged (blocks 8 and 9), which can now be effected without any 
problem, since owing to the reprogramming of the calling terminal the 
required compatibility is provided. After the exchange of data has taken 
place, the programming of the terminal is returned to the original mode, 
that is to say, the normal programming for data communication of the 
terminal (block 10). If no profile indicator is found with a selected 
telephone number, or if there is a profile indicator indeed but no 
reprogramming parameters are found, the data communication link is 
established in the usual mode of the terminal, because it can then be 
assumed that the called terminal also operates in this mode. 
If in block 2 it is established that an incoming call is concerned, there 
is a first check whether a telephone number (DNR) has been received 
together with this call (block 12). If a telephone number has been 
received, the called terminal subsequently searches its memory to find 
whether this telephone number is stored there (block 13) and if this 
number is found, it is checked whether a profile indicator is stored 
together with the telephone number. If also this profile indicator is 
found, the data link will be established in a similar way as described 
hereinbefore with reference to the blocks 5 to 11. 
If no telephone number of the called terminal is received or if this 
telephone number is unknown to the called terminal, or if the telephone 
number is known but no profile indicator has been assigned to it, the link 
will be established thenceforth without the need of reprogramming, to 
check whether the data communication standards of the two terminals are 
compatible. 
FIG. 2 shows a block diagram of a terminal, which will usually be a 
telephone set, which is capable of operating in accordance with the method 
according to the invention. The terminal 1 comprises a telephone number 
memory 2, which can be addressed by means of the figure keyboard 3 of the 
terminal, or by means of a preselection key 4 programmed for a specific 
telephone number. The telephone number memory 2 includes a memory 5 for 
any profile indicators associated to telephone numbers. If a profile 
indicator is associated to a received telephone number, this profile 
indicator can address a table 6, in which table reprogramming parameters 
for each profile indicator are stored. These reprogramming parameters can 
provide the reprogramming of the terminal in a central control unit 7, so 
that the terminal is capable of operating in accordance with a different 
data communication standard. The central control unit 7 provides that the 
data to be transferred via a data line 8 or received via a data line 9 are 
processed according to the standard belonging to the other terminal in 
order to be able to exchange them without any problems with regard to 
compatibility.