The "beep" is slightly different from the standard call-waiting (basically putting the device into a "data-receive" mode), then the standard caller-id mechanism is used to sent the information to the phone.

Standard caller-id devices will not support caller-id w/ call waiting.

Caller ID w/Call Waiting seems to go by a number of different names and, currently, the analog Display Services Interface (ADSI) capable phones seem to be the only devices that can support it.

Analog Display Services Interface (ADSI) (TR-NWT-001273) could be used for both pontaneous Call Waiting Identification (SCWID) (TR-575) or Spontaneous Call Waiting ID with Disposition (DSCWID, TR-NWT-416), where when the call's presented to the already-on-a-call ADSI set, several options "pop up" on the ADSI set. You could choose to answer the call, or route it to your vmail, or put it on hold, or put it to busy and drop.

In a DMS, there's a CPE Alert Signal (CAS) tone that's sent down from the switch to signal that the Caller ID information, via a 202 modem signal, is coming. TR-NWT-000575 specifies an _Alerting Sequence_ consisting of an audible

• * Subscriber Alerting Signal (SAS -- the Call Waiting Tone), and the
• * CPE Alerting Signal (CAS).

I heavily recommend the *full* set of ADSI related documents (or family requirements) FR-12. Bellcore has done some modifications on some documents lately (see TR-416-CORE) so you need the latest set to be up-to-date. The investment, however, pays off fairly quickly if you are really going into the ADSI business.

Bellcore speaks (in SR-3034) about

• * ADSI Script Management Server(s) (ASMS) which would correspond to the Nortel ACMS.
• * feature download services
• * (Telephony) Service Scripts.

A summary;

• * 1st party is engaged in a call (ie., CPE is in off-hook state)
• * some 3rd party calls number of 1st party:
• An _Alerting Sequence_ is sent from the SPCS to the CPE consisting of - an audible Subscriber Alerting Signal (SAS), the Call Waiting Tone, - immediately appended to that a CPE Alerting Signal (CAS) which signals to the CPE that a Call Waiting Event has occured.
• * the CPE now must signal to the SPCS whether it is able to receive the CID information. This is done by transmitting either a - DTMF D (Type 2 CPE), or a - DTMF A (Type 3 CPE) to the SPCS:
• * Having received such a positive ACKnowledge the SPCS now starts to transmit the CID information (in the standard 1200 bps FSK way) to the CPE. During that transmission, which may last a maximum of 1 second, the voice-path is muted.
• * The CPE, then, displays the CID information on its screen.

The ADSI provides a lot more than just CIDCW functionality. In effect, it is a standard which should provide so-called screen based features (in the sense of applications like home-bankning, running on a server system) for screen phones. On the other hand the off-line capabilities (via so-called ADSI service scripts resident on each CPE) enable the user to visually manage her calls (like CIDCW) in a convenient manner.

Two ADSI compliant CPEs:

• Philips ScreenPhone P100 (Philips Home Services, Inc.)
• Nortel PowerTouch 3xx (Nortel)

• * Type 2 CPE supporting (amongst other things)

• - CND (Calling Number Delivery, in Bellcore speak)
• - CNAM (Calling Name Delivery)
• - CIDCW (Calling Identity Delivery on Call Waiting).
  • * Type 3 CPE fully support the Analog Display Services Interface (ADSI). (see TR-NWT-001273)

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