Polarity reversal during Caller ID display 1

[Guest_imported]

Greetings to All!

I have been beset with this problem of implementing Caller ID display on the PBX analog line, and have been given the standard ETS 300 659-1 to refer to. But these funny standards only talk of what is required and skirt everything else, leading to much confusion about the exact method of doing it right.

I now know that the telephone line feeding voltage polarity is reversed to alert the TE about any CID info to be displayed. The standard also says the line polarity is restored after CID display. But WHEN? HOW? The standard simply raises it's hands saying it is out of scope!!

I request some help in this regard. Pls tell me where do I look for the specs about when to restore the line polarity after CID display. I shall be grateful (Probably even my boss will be grateful!!)

Thanx in advance,
Krishna.

 

[PAEricksen]

CID is generally inserted between the second and third ring cycle. 12-18 seconds after call origination.

 

[kenm16]

Krishna:
Much depends on where your PBX will be used. The North American CallerID implementation is based on a Bellcore (now Telcordia) (see

http://www.telcordia.com)

standard. Your email refers to one of the ETS documents from ETSI (

http://www.etsi.org)

which is the European Telecommunications Standards Institue, and their docuemnts attempt to cover the EU requirements. But even country to country variances occur in the EU.
Of course there are also different types of caller ID (commonly known as Type 1, 2, 2.5, and 3). The ETS and Bellcore documents that I am familiar with specify the requirements for the telephony device, not the switch (or PBX as in your case). These documents tend to make the requirements for the CPE such that it will at least meet the timing of different switches; you will want to find a document more on the switch side of things, which I think Telcordia will have if that is the requirement that you have to design to.
I hope that this has, at least, been helpful information.