# Glossary: IVR

### TelcoBridges and IVR capabilities

TelcoBridges products support IVR functionality via dedicated digital signal processor (DSP) chips, or via voice over IP (VoIP) chips.

* With release 2.4 and older, IVR DSPs are required for any IVR functionality.
* With release 2.5, IVR DSPs are required only for playing/recording, as digit/tone collection and generation can be handled using VoIP chips.
* With release 2.8.111 and above, there is also a possibility to use VoIP chips for playing/recording with special licensing. Please contact TelcoBridges support team to learn more about that feature.

### Hardware IVR capabilities on TMedia products

* In the case of the Tmedia [TMG800](https://docs.telcobridges.com/wiki/TMG800) , Tmedia [TMG3200](https://docs.telcobridges.com/wiki/TMG3200), Tmedia [TMG7800](https://docs.telcobridges.com/wiki/TMG7800) and Tdev [TMP6400](https://docs.telcobridges.com/wiki/TMP6400)[TM1000](https://docs.telcobridges.com/wiki/TM1000), IVR DSP or VoIP chips can be included during the initial purchase or added subsequently via hardware upgrade.

### Calculating the number of IVR channels required

The number of IVR channels required in a system depends on the type of calls handled by the system, and the type of IVR operations performed. Below we explain how to calculate IVR resources requirements.

#### IVR Hardware density

IVR DSP chips and VoIP chips can both provide IVR functionality. When both are present on the hardware, IVR DSPs are used first (to make VoIP resources available for actual VoIP RTP stream), and fall-back to VoIP channels when no IVR DSP resources are available.

**IVR DSP chips**

* Each IVR DSP chip can provide 512 channels of IVR functionality (except when Play and Record are both used at the same time, where density is 300 channels per chip)
* Tmedia [TMG3200](https://docs.telcobridges.com/wiki/TMG3200), Tmedia [TMG7800](https://docs.telcobridges.com/wiki/TMG7800) and Tdev [TMP6400](https://docs.telcobridges.com/wiki/TMP6400) can have between 1 and 4 DSP chips.
* Tmedia [TMG800](https://docs.telcobridges.com/wiki/TMG800) and Tdev [TMP800](https://docs.telcobridges.com/wiki/TMP800) can have 1 DSP chip.

**VoIP chips**

* Each VoIP chip can provide 341 channels of IVR functionality (although some calls will require two VoIP channels, one for RTP stream, one for Play/Record stream)
* Tmedia [TMG3200](https://docs.telcobridges.com/wiki/TMG3200), TMedia [TMG7800](https://docs.telcobridges.com/wiki/TMG7800) and Tdev [TMP6400](https://docs.telcobridges.com/wiki/TMP6400) can have between 1 and 16 VoIP chips.
* Tmedia [TMG800](https://docs.telcobridges.com/wiki/TMG800) and Tdev [TMP800](https://docs.telcobridges.com/wiki/TMP800) can have 1 or 2 VoIP chips.

<br>

#### Number of IVR channels required

The following table represents the number of IVR resources required for non-joined call legs, or for joined call legs that are temporarily un-joined due to playing to one of the two joined legs:

|                                  | Non joined call leg | Joined call leg, temporarily un-joined for playing to on of the two legs |
| -------------------------------- | ------------------- | ------------------------------------------------------------------------ |
| None                             | 0                   | 0                                                                        |
| Digit/tone collection/generation | 1                   | 1                                                                        |
| Playing audio                    | 1                   | 1                                                                        |
| Recording audio                  | 1                   | 1                                                                        |
| Tone + playing + recording       | 1                   | 1                                                                        |

\
The following table represents the number of IVR channels required (*per call leg*) for IVR functions on joined call legs

|                                  | For a leg joined to a TDM leg | For a leg joined to a VoIP leg |
| -------------------------------- | ----------------------------- | ------------------------------ |
| None                             | 0                             | 0                              |
| Digit/tone collection/generation | 1                             | 0                              |
| Recording audio                  | 1                             | 1                              |
| Tone + recording                 | 2                             | 1                              |

\
The following table represents the number of IVR channels required (*per call leg*) for tone relay on joined calls.

|                       |     | Call leg B |                      |                      |                       |
| --------------------- | --- | ---------- | -------------------- | -------------------- | --------------------- |
|                       |     | TDM        | VoIP (in-band relay) | VoIP (RFC2833 relay) | VoIP (SIP Info relay) |
| Call leg A            | TDM | 0          | 0                    | 0                    | 0                     |
| VoIP (in-band relay)  | 0   | 0          | 0                    | 0                    |                       |
| VoIP (RFC2833 relay)  | 0   | 0          | 0                    | 0                    |                       |
| VoIP (SIP Info relay) | 0   | 0          | 0                    | 0                    |                       |

Notes:

* The tables above count only the IVR DSP resources. To that number, one VoIP resource must be added if the call leg is of type VoIP.
* The weight of a VoIP resource may vary according to the codec used (between 58 and 341 channels per VoIP chip, depending on the codec)
* The weight of a VoIP resource used for IVR is the same no matter if tone/play/record or all of them is used (341 channels per VoIP chip)


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