in the Hong Kong Sar?

In the Hong Kong SAR, why is the fax still regarded as a serious medium for official correspondence?

As the other commentators point out, fax dialing is the same as phone dialing, so you dial your country's exit code, then the destination country's dialing prefix, and then the number. Some countries may have different domestic and international dialplans (for instance, Israel has a "0" used in domestic dialing that should be omitted when calling Israel from outside the country), but the same steps apply to both voice and fax calls. In most cases (if your fax is only a few pages long and is being sent to a non-blacklisted number), a free service like HelloFax would work fine for outbound-only transmission. If you routinely need both inbound and outbound fax capabilities, you have several options depending on your budget and technical expertise. HelloFax would be one of several simple methods for uploading a document, sending it over fax, and retaining a fax number for bidirectional faxing over the Internet, starting at $9.99/month. A few options are outlined at How can I get a fax number for free?, but for worldwide transmission without any third-party blacklisted restrictions (like HelloFax sometimes imposes on high-cost termination), your best long-term bet might to use a free Digium Fax for Asterisk license (Fax for Asterisk) with a Twilio or Flowroute SIP DID on an Asterisk PBX server. Below is a USD comparison for sending a 5-page fax to Bengaluru, India from a US DID in 2015, assuming the recipient uses a Group 3 T.30/T.4 fax machine sending 1 page per 15 seconds. Twilio. Monthly charge. $1 per DID/virtual telephone number Usage charge. $0.025/minute x 2 minutes [based on current billing increments] = $0.05 per 5-page fax Flowroute. One-time charge. $1 per DID/VTN Monthly charge. $1.25 per DID/VTN Usage charge. $0.0265/minute x 2 minutes [based on current billing increments] = $0.053 per 5-page fax The cost is especially competitive if you have another use for the DID anyway (like placing voice calls), and if your some of your recipients have been flagged by a SaaS fax provider as using high-cost/"high-risk" numbers.