---
title: mixToTelephonyUplink
framework: avfaudio
role: symbol
role_heading: Instance Property
path: avfaudio/avspeechsynthesizer/mixtotelephonyuplink
---

# mixToTelephonyUplink

A Boolean value that specifies whether to send synthesized speech to an active call.

## Declaration

```swift
var mixToTelephonyUplink: Bool { get set }
```

## Discussion

Discussion This property has no effect when there isn’t an active call.

## See Also

### Directing speech output

- [usesApplicationAudioSession](avfaudio/avspeechsynthesizer/usesapplicationaudiosession.md)
- [outputChannels](avfaudio/avspeechsynthesizer/outputchannels.md)
- [write(_:toBufferCallback:)](avfaudio/avspeechsynthesizer/write(_:tobuffercallback:).md)
- [AVSpeechSynthesizer.BufferCallback](avfaudio/avspeechsynthesizer/buffercallback.md)
- [write(_:toBufferCallback:toMarkerCallback:)](avfaudio/avspeechsynthesizer/write(_:tobuffercallback:tomarkercallback:).md)
- [AVSpeechSynthesizer.MarkerCallback](avfaudio/avspeechsynthesizer/markercallback.md)