the maximum length of phone number is 9 digits long.
what is the maximum length of phone number?
9 digits long
the e.164 standard of the international telecommunications union is an international numbering plan and establishes a country calling code ("country code") for each member organization. country codes are prefixes to national telephone numbers that denote call routing to the network of a subordinate number plan administration, typically a country, or group of countries with a uniform numbering plan, such as the nanp. e.164 permits a maximum length of 15 digits for the complete international phone number consisting of the country code, the national routing code (area code), and the subscriber number. e.164 does not define regional numbering plans, however, it does provide recommendations for new implementations and uniform representation of all telephone numbers.
telephone numbering plan
since threema's servers are located in switzerland, they are subject to the swiss federal law on data protection. the data center is iso/iec 27001-certified. linking a phone number and/or e-mail address to a threema id is optional; when doing so, only checksum values (sha-256 hmac with a static key) of the e-mail address and/or phone number are sent to the server. due to the small number of possible digit combinations of a telephone number, the phone number associated with a checksum could be determined by brute force. the transmitted data is tls-secured. the address book data is kept only in the volatile memory of the server and is deleted immediately after synchronizing contacts. if a user chooses to link a phone number or e-mail address with their threema id, they can remove the phone number or e-mail address at any time. should a user ever lose their device (and their private key), they can revoke their threema id if a revocation password for that id has been set.
threema