University Telephone System
BLF & SCA: Busy Lamp Field & Shared Call Appearance
Shared Call Appearance (SCA)
A Shared Call Appearance (SCA) is an appearance of another user's line on your phone. This is typically used for call coverage of another user's line.
An example of call coverage follows: User A is the assistant for User B. User A would have her own primary line and a separate line for User B listed on her line keys. Both keys would be labeled with a 5-digit extension number. Both phones would ring (by default) when a call came in to User B's line and either user could answer that line. User A could manually change the ring tone or silence the ring tone for User B's line from the phone itself. If User A pressed the button for User B when there was not a call ringing in, User A would receive dial tone to make a call out using User B's line. This key does NOT act as a speed dial.
Note: There is a limit of 5 SCAs per phone.
The picture below shows a VVX 410 with SCAs programmed.
Enhanced Busy Lamp Field (EBLF)
An Enhanced Busy Lamp Field (EBLF) allows you to monitor the status of another user. The EBLF also allows you to answer that user's phone if desired; although it does not ring, it will only flash on the designated button. The EBLF is labeled with the user's name. You cannot use this key to make an outside call using that line, when you press the button, it acts as a speed dial to call that user.
Note: There is a limit of 35 EBLFs per phone.
The picture below shows a VVX 500 with EBLFs assigned.
The chart below shows a quick comparison between EBLF and SCA.
EBLF (Busy Lamp Field)
SCA (Shared Call Appearance)
A "Bare SCA" is a device that does not have its own primary number and shares a number with another VoIP phone. The easiest way to think about this is a scenario that has multiple IP phones with the same primary extension number, or a "bridged" IP phone. A few examples of where we have seen this setup are as follows:
- Office phone for User A is extension 71234 in room 123 and there is also a phone in the classroom/lab with extension 71234 in room 157
- Nurses Station may have 4 Polycom VVX 410 phones all with the same extension number of 24783
A phantom number is a number that does not appear on any device. This is generally a number that when dialed, is forwarded to another number (internal or external) An example may be a help desk number. This is a phone number that when called, forwards to an external answering service and does not ring on a device.
A secondary number may be a user's second line. In most cases, this is not needed on the new system. The new system allows your primary extension to take up to 3 calls per line, therefore a secondary number is not needed for this purpose. If you currently have a second line on your phone that is only assigned to you, we can have that line removed from the new setup. If this second line is published and it is dialed directly from the outside world, it could be kept and programmed on your second line key.