Tone Generation

Types of Tones

The CSP lets you transmit address signaling and call progress tones. Each tone type is available for both µ-law and A-law. You can generate the following tones:

• Dual Tone Multi-frequency (DTMF)

• Multi-frequency R1 (MFR1)

• Multi-frequency R2 (MFR2 – backward and forward)

• Call Progress Tone Patterns (CPT4)

• Calling Card Prompt (Bong Tone)

The transmit tones for DTMF, MFR1, MFR2, and CPT4 are non-blocking. That is, when you generate one of these tones, it can connect to any number of channels. For example, a single DSP chip configured to generate MFR1 tones can provide MFR1 tones to all 2,048 ports in the CSP.

In contrast, the Calling Card Prompt (or Bong Tone) is a blocking tone that can connect to only one channel at a time. The Bong Tone is a blocking tone because it varies over time, so it must be played from start to end. A DSP chip can generate up to sixteen instances of the Bong Tone. When more than one channel requires a Bong Tone, the channels connect simultaneously to an instance of the Bong Tone, and remain connected from start to finish.

On the DSP-ONE card you can configure more than one DSP chip to generate Bong Tone on a single DSP card. But do not configure more than one transmitter on a DSP card to generate MFR1/MFR2, DTMF, or call progress tones of the same encoding format (µ-law /A-law). If you do, the configuration message receives a negative acknowledgment (NACK). Before you add a second CPT4 to a DSP chip, you must remove CPT4 from the first DSP chip, even if the DSP chip is out of service.

Tone Generator Attributes summarizes the attributes of the tone generators.

Table 9-5 Tone Generator Attributes

For MFR2 transmission and reception, every card that has an MFR2
receiver must also have a corresponding forward and backward MFR2 transmitter (or Universal transmitter for the DSP Series 2 card). To duplicate the generation of a tone for redundancy, configure the tone function on separate cards.

Address Signaling Tones

For outbound calls, configure the CSP to generate DTMF, MFR1, or MFR2 address signaling to the downstream CSP or device. To initiate outpulsing, use the Outseize Control (0x002C) message with an action of "Outpulse Stage N Address Data." Data ICBs in the Outseize Control (0x002C) message indicate the signaling tone type and the source of the digits. Digits can be specified in the Outseize Control (0x002C) message itself, or they can be taken from a list of previously-inpulsed digits. Digit durations are set by the PPL component on the associated line card.

Example: You set the following durations using PPL timers, and you modify them using the PPL Timer Configure message (0x00CF):

• delay until the start of the first digit

• "on" time of the first digit

• "on" time of subsequent digits

• "off" time between all digits

For DTMF and MFR1 digits, outpulsing can also be initiated using the Outpulse Digits (0x0020) message. Within that message, the host can specify the following durations:

• delay until the start of the first digit

• "on" time of the first digit

• "on" time of subsequent digits

• "off" time between all digits

Durations are specified in units of 10 milliseconds. Actual outpulsed durations, however, are truncated to 20 millisecond intervals. So a digit duration specified as a multiple of 20 milliseconds is outpulsed with that duration, while other digit durations are shortened. For example, digits with a specified duration of 20, 40, or 60 milliseconds are outpulsed with those durations. But a digit with a specified duration of 30 milliseconds is truncated to have a 20 millisecond duration upon outpulsing. Similarly, 50 milliseconds is outpulsed as 40 milliseconds, 70 milliseconds is outpulsed as 60 milliseconds, and so on. Because of the truncated durations, you should set a minimum outpulse duration for 20 milliseconds or greater.

The host dynamically configures the dBm levels of DTMF, MFR1, and MFR2 transmit tones, using the Tone Configure message (0x0031). Power levels are updated globally for each tone type. For DTMF tones, you must specify the dBm level for both low-band and high-band frequency components. For MFR1 and MFR2 tones, you must specify only one dBm level.

Table 9-6 DTMF digit specifications

Table 9-7 MFR1, MFR2 digit specifications