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Five-digit internal extensions from June 2009 - An Update

Dear Colleagues,

The transition of 4-digit internal extension to 5-digit will be resumed on Saturday, 30 May 2009.

Adding a Prefix “6” to Extension Numbers

From 1 June 2009, you will need to add the digit “6” to the current 4-digit extension number when making an internal call on campus.  For example, if a current extension number is “nnnn”, you will need to dial the numbers “6nnnn” to reach that same extension.   

The switch will affect only internal dialling; there will be no change for external calls coming in to the same extension, i.e. a person dialling in from outside the University will still dial “6516 nnnn”.   

To ease the transition period, there will be a Call Announcement to remind caller to add the digit “6” (if you continue to dial the 4-digit extension), and to re-dial using the 5-digit extension.

Rebooting of Internet Protocol (IP) Telephones

As part of this transition, your IP telephone may be rebooted several times between 1.00am Saturday, 30 May to 7.00am Monday, 1 June 2009. Records for missed calls, calls received and calls dialled will be cleared from your telephone as a result of this rebooting process. All other information will remain intact. Please clear your voicemail (if any), before 30 May 2009.

For additional information, please refer to the Frequently Asked Questions at You may also call NUS IT Care at 6516 2080 or email for assistance.   

Thank you.   

FAQ: Move from 4-digit to 5-digit extensions
Q1: What should I do if my telephone is not working after the transition?
Ans: Please switch OFF the power supply to the IP phone and wait for about 3 seconds
before turning it ON again. The telephone will take about 5 minutes to boot up. If
your telephone is still not working, please contact IT Care at 6516 2080, or
Q2: What will happen to the call history information in my telephone?
Ans: Your records for missed calls, calls received and calls placed will be cleared from
your IP Phone as a result of the rebooting process. All other information will remain
Q3: Should I change my office telephone number on my name card and office
Ans: No. Your office telephone number will not be affected if you are using the 8-digit
telephone number, e.g.6516 nnnn.
Q4: Will my voicemail be affected?
Ans: No, if you access voicemail from your own IP phone. If you are accessing your
voicemail from another IP phone other than yours, you will need to key in the 5-digit
extension instead of the original 4-digit number. There will be no change to your PIN
number. Please remember to clear your voicemail before 30 May 2009.
Q5: Can a caller leave a message on my telephone during the transition period
       of 30 May to 1th June 2009?
Ans: No. The voicemail service will only resume on 1st June 2009.
Q6: Will my speed-dial or personal directory be affected?
Ans: Yes. Please update your internal call directory with the new 5-digit extensions.
Q7: Will I need to add the prefix "6" when dialling emergency numbers?
Ans: No, emergency numbers will not be affected. For e.g., Campus Security will remain
contactable at 9 6874 1616, ambulance services at 9995 and the Police at 9999.

For common queries please click here or contact your department's Phone Administrator.


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