IP Phone FAQ

Q: What is Voice over IP (VoIP)?

Q: Why change to VoIP?

Q: What is the difference between the old PABX and the new IP Telephony (IPT) system?

Q: How to apply for an IP phone?

Q: I heard that I need to change my phone number, can I keep my extension?

Q. Can I keep my old number?

Q: Do I need to dial "0" + full eight-digits to make calls between the two phone systems (PABX and IPT)?

Q: Can I make IDD (long distance) call with the IP phone?

Q: How reliable is IP phone system? I have heard bad comments from some VoIP users.

Q: I heard that data and voice share the same network, will they interfere with each other?

Q: Will voice quality degrade while my computer is running bandwidth demanding applications?

Q: What should we do with the old analog phones?

Q: What about fax machines, modems and alarm systems that must work with analog signals?

Q: I don't want the others seeing my telephone number when I make an external call. Can I hide the display of my number?

Q: How to reset voice mail password and change location, phone features and user details of a phone?

Q: How can I create my Personal Address Book?

Q: How can I change my Browser password and phone PIN?

Q: What is Voice over IP (VoIP)?

Voice over IP (VoIP) is a digital technology that allows voice and video calls to be conducted over an public or private IP network using a combination of computers and IP phones at both ends (as opposed to the PBX phone system using analogue technology to carry voice-only calls over a public or private telephone network using a combination of telephones and fax machines at both ends). Through the appropriate digital gateway, the digital IP telephony (IPT) System is able to communicate seamlessly with an analogue PBX phone systems over the analogue telephone network and vice versa .

Q: Why change to VoIP?

The old PABX system we currently used is over 18-year old and is already reached its life cycle. There is great potential risk of system breakdown due to hardware failure which may impact the majority of the university community. So it is considered necessary to migrate the phone users from the PABX system to the newest VoIP system as soon as possible.

Q: What is the difference between the old PABX and the new IP Telephony (IPT) system?

VoIP provides more versatile and high-quality phone service than that of the old PABX. All phones will have Caller ID and access to the cooperate directory. In addition, a large LCD display on the phone set allows the University to develop its own voice/data applications and services.

Q: How to apply for an IP phone?

Contact the General Office of your department to submit a request through the 'CSC Work Request On-line Submission System' and our staff will process your request as soon as possible

Q: I heard that I need to change my phone number, can I keep my extension?

The University has acquired the prefix 3442 for the IPT system. Renumbering is therefore required whenever a PBX device is migrated to the IPT system. Unless there is a conflict, all new phone numbers will assume the format of <3442> . For example, 2788-7658 will be changed to 3442-7658.

Q. Can I keep my old number?

The University has to return the old numbers occupied by the PBX system to OFTA for re-deployment within a reasonable time frame. So we cannot keep the old numbers.

Q: Do I need to dial "0" + full eight-digits to make calls between the two phone systems (PABX and IPT)?

No. To minimize impact on the phone service during migration, special arrangement in setting up an inter-trunk to link up the PBX and IPT systems is made. As a result, a user on either phone system can make call by just dialing the recipient’s 4-digit extension number regardless of which phone system the recipient’s phone number actually belongs to.

Q: Can I make IDD (long distance) call with the IP phone?

No. Similar to that of the PABX system, you need to use IDD calling card to make IDD calls in the IP phone system.

Q: How reliable is IP phone system?

I have heard bad comments from some VoIP users. The IP phone system is composed of a Cisco Unified Communications Manager Cluster, a Unity Voice Mail System, Voice Gateways and Cisco IP phone sets inter-connected through Cisco routers and switches. The IPT core equipments and core network are built with fully redundancy and highest priority is given to the voice traffics to ensure best quality and reliability.

Q: I heard that data and voice share the same network, will they interfere with each other?

Although the voice and data traffic shares the same network cable, they are running on separate VLANs. So that they will not interfere with each other.

Q: Will voice quality degrade while my computer is running bandwidth demanding applications?

Since voice quality is sensitive to jitter (delay), highest priority is given to the voice traffics to ensure best quality and reliability. Therefore voice quality is ensured even your computer is running bandwidth demanding applications while using the IP phone.

Q: What about fax machines, modems and alarm systems that must work with analog signals?

We will place such fax machines, modems and alarm systems behind a voice gateway, which should work with existing analog devices and converts them to run on the IP phone system.

Q: What should we do with the old analog phones?

We will collect the old analog phones while deploying the new IP phone sets. Normally, a 3-month call forward service or playing an announcement to inform the caller of your new phone number will be provided by default.

Q: I don't want the others seeing my telephone number when I make an external call. Can I hide the display of my number?

If you do not want your phone number displayed on an external call, you can dial <0133> .

Q: How to reset voice mail password and change location, phone features and user details of a phone?

Contact the General Office of your department to submit a request through the 'CSC Work Request On-line Submission System' and our staff will process your request as soon as possible.

Q: How can I create my Personal Address Book?

Please click here for the detailed procedures.

Q: How can I change my Browser password and phone PIN?

Please click here for the detailed procedures.

csc@cityu.edu.hk