Home » IT Services News » IT Services News No. 167 Jan - Feb 2014 » Free International Calls to Overseas Educational and Research Institutions via NRENum.net Service

Free International Calls to Overseas Educational and Research Institutions via NRENum.net Service

What is NRENum.net service?

We are piloting a new telephone service called NRENum.net.  The NRENum.net service is an end-user ENUM (Electronic Number Mapping System) service run by TERENA through which participating institutions can make free international calls over the Internet with counterparts who are also using the NRENum.net service.  This service is primarily for NREN (National Research and Education Networking organizations) in the education sector and more than 180,000 phone numbers are now reachable via this service. 

Hong Kong participated in the NRENum.net service via HARNET (Hong Kong Academic and Research NETwork) in February 2013.  This new service is now ready for use in the University and we would like to solicit inputs and feedback from our users for the pilot run.

Who can use the service?

The NRENNum.net service is available to anyone who is using a Cisco IP phone on campus (phone number with 3917 as prefix).  No registration is required and one can use it immediately.

If your IP phone supports video calls, you can also make video calls with your counterparts who are using video phones or video conferencing systems.  To check whether a number is reachable via the NRENum.net service, you can look up the phone directory at http://crawler.nrenum.net.

The major NRENs who have joined the NRENnum.net include United Kingdom, the States, France, Australia, and New Zealand. For the latest membership list of NREnum.net, please refer to http://confluence.terena.org/display/NRENum/Members.

Once a country’s NREN joined nrenum.net, the educational or research institutions in that country can opt in the NRENnum.net service. In Australia, more than 20 universities and research institutions have joined this service and are connected in the NRENum.net infrastructure (http://wiki.aarnet.edu.au/display/UCX/Home#Home-Currentlyconnected).

List of country codes

How to use it?

It is simple to use the service.  Simply use your Cisco IP phone (phone number starts with 3917) and dial

‘64’ + ‘country code’ + ‘area code’ + ‘phone number’

For examples, dial ‘64 44 xxxxxxxxx’ to make a call to UK and ‘64 61 xxxxxxxx’ to Australia.

It may take a bit longer (around 10 seconds) to make a call compares to making a local call.  If a call cannot be established for reasons, such as the phone number is unreachable by NRENum.net, you will hear a busy tone.  For receiving calls from overseas, please invite the caller to call your phone number (i.e., 852 3917 xxxx) following the NRENnum.net service calling procedure of his/her institution.

Please try out this new service and give us your feedback by sending an email to the undersigned or to ithelp@hku.hk.


Kenneth Yip
Tel: 3917 7973
Email: kkyyip@hku.hk