reference is now made to fig1 which is a schematic diagram illustrating operation of an indirect dialing system 10 , according to a preferred embodiment of the present invention . a first communication device 12 , for example a mobile telephone , may be contacted via a telephone number 14 supplied by a provider of the device , by methods known in the art . device 12 is herein also termed the destination device or the destination telephone , and is assumed to be coupled to a telecommunication network 28 . telephone number 14 , also herein termed the destination telephone number , comprises a number in an industry - standard e . 164 format , described in the background of the invention , and network 28 supports use of numbers in this industry - standard format . preferably , a user 16 of the destination device informs an operator of network 28 of a mapping between the destination telephone number and an identifier 18 of the user . alternatively , the operator is informed of the mapping by a person other than user 16 who is acquainted with both the destination telephone number and identifier 18 of the user . identifier 18 may comprise any alphanumerical string associated with user 16 . for example , the string may comprise a license number of a car driven by the user , a social security number of the user , a passport number of the user , a number of a credit card registered to the user , or any other type of number which may be used to identify user 16 . most preferably , the alphanumerical string is assigned to user 16 by an entity , independent of the user , which is authorized to issue the string . for example , the entity may be an official body such as a vehicle licensing authority which is authorized to issue a string as a car license number , or a ministry of social services which is authorized to issue a social security number . alternatively , the entity may be a credit card company which is able to issue a credit card number . other entities which are authorized and / or are able to issue types of numbers will be familiar to those skilled in the art . typically , each type of string is associated with a corresponding object , for example , the license number is associated with the corresponding license plate , and the passport number is associated with the corresponding passport . it will be appreciated that the license number , the passport number , and other strings used as identifier 18 , may include letters . identifier 18 most preferably also comprises a prefix to the string , the prefix serving to classify the type of identifier being stored . for example , if the identifier is a social security number , the prefix may be ssn or the numerical equivalent of ssn , i . e ., 776 . it will be appreciated that identifier 18 is in a format different from the industry - standard format of telephone number 14 . alternatively , one prefix is used as an indicator to network 28 that an indirect dialing method is being invoked , and that the number dialed is not an industry - standard telephone number . the mapping between identifier 18 and telephone number 14 is stored within a lookup table 20 in a memory 22 , the memory being accessible to a communication server 29 comprised in network 28 . lookup table 20 may comprise other mappings between identifiers and destination telephone numbers . for example , user 16 may inform the operator of system 10 of another identifier 24 of the user , so that table 20 comprises a first mapping between identifier 18 and the destination telephone number , and a second mapping between identifier 24 and the destination telephone number . furthermore , table 20 typically comprises mappings , substantially similar to those described above for user 16 , for other users of system 10 . a caller 26 uses a second communication device 30 to communicate with telecommunication network 28 . typically , device 30 comprises a mobile telephone , a landline telephone , or a voice over internet ( voip ) connection . to communicate with the network . device 30 is herein also termed the originating device or originating telephone . caller 26 wishes to contact user 16 of destination device 12 , and uses originating telephone 30 to dial one of the identifiers of the destination device , herein assumed to be identifier 18 . network 28 recognizes identifier 18 as a dialed input which is not in the industry - standard format used by the network , for example , by noting the identifier &# 39 ; s prefix , and routes the dialed identifier to server 29 . the server uses memory 22 to look up telephone number 14 using identifier 18 as a pointer within table 20 , and provides the telephone number to network 28 . network 28 then completes the connection between originating device 30 and destination device 12 , substantially as if caller 26 had dialed telephone number 14 . it will be appreciated that in order for caller 26 to communicate efficiently with user 16 via device 12 , caller 26 is preferably conversant with at least one specific identifier associated with the device . some types of identifiers , such as car license numbers , may be available publicly . other types of identifiers , such as a social security number , may be restricted in availability , but may be known to caller 26 , for example , by user 16 providing the social security number to the caller . it will also be appreciated that certain types of identifiers , such as car license numbers , may need to be further identified so as to avoid ambiguity . for example , a license number may be repeated in more than one state or region of a country . when such ambiguity may occur , most preferably one or more extra characters , corresponding to the state or region in the case of car license numbers , are added to form the identifier . alternatively or additionally , in the case of ambiguity server 29 recognizes from accessing table 20 that an ambiguity exists . the server then informs caller 26 of the ambiguity , and attempts to clarify the ambiguity by informing the caller of possible choices . for example , if identifier 18 is a car license number without a prefix identifying the state , server 29 may inform caller 26 of multiple entries in table 20 , and ask the caller to choose between states , or between area codes of the ambiguous entries . fig2 is a schematic diagram illustrating operation of an alternative indirect dialing system 50 , according to a preferred embodiment of the present invention . apart from the differences described below , the operation of system 50 is generally similar to that of system 10 , so that elements indicated by the same reference numerals in both systems 50 and 10 are generally identical in construction and in operation . caller 26 , using communication device 30 , is a first driver of a car 52 . user 16 , using communication device 12 , is a second driver of a car 56 . ( for clarity , neither caller 26 nor user 16 are shown in fig2 ). user 16 provides a license number 60 of car 56 to the operator of network 28 , the license number serving as an identifier for communication device 12 . license number 60 and telephone number 14 of communication device 12 are stored as a mapping in lookup table 20 in memory 22 . the first driver ( caller 26 ) wishes to call the second driver ( user 16 ). car 52 comprises an imaging system 54 , which is able to image and isolate a car license plate 58 of car 56 , and which is able to recover license number 60 from the image . such systems are well known in the imaging art . in order to call the second driver , the first driver activates imaging system 54 , which images plate 58 and recovers license number 60 from the image . system 54 is coupled to communication device 30 . after recovering license number 60 , system 54 activates device 30 and provides the recovered license number to the device . device 30 in turn dials license number 60 , with appropriate prefixes as necessary , so that the dialed number appears to network 28 as an identifier . network 28 receives the dialed identifier and routes it to server 29 , which accesses table 20 to determine telephone number 14 . server 29 provides network 28 with the number in order to place a call to device 12 in car 56 , substantially as described above with reference to system 10 . when the second driver accepts the call in device 12 , devices 12 and 30 are connected by network 28 and the first and second drivers are able to communicate via the devices . the description of systems 10 and 50 has assumed that devices 12 and 30 are operative in one communication network 28 . it will be appreciated , however , that communication devices 12 and 30 , in systems 10 and / or 50 , may be operative in separate communication networks which couple together in order for the devices to communicate , by methods known in the art . for example , communication device 12 may comprise a landline telephone operative within a public switched telephone network ( pstn ), and communication device 30 may comprise a mobile telephone operative within a cellular network . the scope of the present invention thus comprises communication devices operative in one or more communication networks . it will be appreciated that lookup table 20 may be comprised of more than one sub - table , the sub - tables being coupled together so that mappings between identifiers and telephone numbers may be stored , and so that a specific identifier may be used as a pointer to recover the respective telephone number associated with the identifier . similarly , memory 22 may be comprised of more than one sub - memory which may be localized with respect to network 28 or remote from the network . furthermore , table 20 may be stored in a centralized form within memory 22 , or in a distributed form within the sub - memories . it will thus be appreciated that the preferred embodiments described above are cited by way of example , and that the present invention is not limited to what has been particularly shown and described hereinabove . rather , the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove , as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art .