Type II Caller ID (Call Waiting Caller ID) — CallerID.com Device Support

WHAT IS TYPE II CALLER ID?
Type II Caller ID is the caller ID signal delivered while a call is already in progress. When a second caller tries to reach the same number, the phone company sends a call-waiting beep and, within that beep, a brief FSK data burst identifying the second caller. This is distinct from Type I (standard Caller ID), which is delivered between the first and second ring before the call is answered.

TYPE I vs TYPE II SUMMARY
- Type I (Standard Caller ID): delivered between rings, before answer, line is idle/on-hook.
- Type II (Call Waiting Caller ID / CWCID): delivered mid-call during the call-waiting tone, line is active/off-hook.
Both use the same Bell 202 FSK modulation and carry the same data: caller number, caller name, date/time.

HOW DOES TYPE II WORK?
1. First call is active (line off-hook).
2. A second call arrives at the central office.
3. CO plays the Subscriber Alerting Signal (call-waiting beep).
4. Within the beep, CO injects a standard FSK Caller ID burst for the second caller.
5. Subscriber can switch to the second caller or ignore.
The carrier must have both Caller ID AND Call Waiting subscribed for Type II to work.

WHOZZ CALLING (ANALOG / POTS) — FULL TYPE I AND TYPE II SUPPORT
Yes. All Whozz Calling models monitor the analog line continuously regardless of call state. When the FSK burst arrives mid-call (Type II event), the device decodes it and broadcasts the call record over UDP port 3520 — exactly the same format as a Type I event. The POS or CRM receiving the UDP data sees no structural difference between a Type I and a Type II record.

Carrier requirement: the subscriber must have both Caller ID service AND Call Waiting active through their telephone carrier. Without both, the carrier will not transmit the Type II FSK burst.

VERTEX (VOIP / SIP) — NOT APPLICABLE
The Type I/II distinction is an analog-telephony concept and does not apply to VoIP. On a SIP trunk, every incoming call arrives as a separate SIP INVITE dialog with caller ID carried in the P-Asserted-Identity or From header — completely independent of any other active call. The Vertex captures that identity for every SIP INVITE it sees, whether another call is in progress or not.

DEVICE SUPPORT QUICK REFERENCE
- Whozz Calling Ethernet (2/4/8/16-line): Type I YES, Type II YES (carrier must have CID + Call Waiting)
- Whozz Calling USB: Type I YES, Type II YES (same carrier requirement)
- Vertex: Type I YES (SIP INVITE), Type II N/A (SIP delivers CID per call leg natively)
- Vertex Solace: same as Vertex

ONE-LINE ANSWER FOR SUPPORT TICKETS
"Yes — Whozz Calling devices support both Type I (standard) and Type II (call-waiting) Caller ID on analog lines. The Vertex handles VoIP where caller ID is delivered per call natively, so Type I/II doesn't apply there."