| Attributes |
| Name | Required | Request-time | Type | Description |
| title | false | true | String | (optional) - If a string is provided here, the call button on a WAP/HDML device will be entitled. In order to work well with a broad range of devices, keep the title as short as possible. |
| css_class | false | true | String | (optional) - sets a css class for this phone tag |
| br | false | true | int | number of line breaks after phone link (default: 1) |
| voice_input | false | true | String | (optional) - Sets a phrase the voice browser is reacting on.
Pass an empty string, if voice triggering should be disabled. In this case you should use voice_dtmf to correlate the call with a given DTMF event. Otherwise the outgoing call could not be triggered at all. |
| voice_dtmf | false | true | String | (optional) - sets a DTMF key as call trigger for voice browsers, e.g. "1", "2", ... ,"0", "*", "#" |
| voice_timeout | false | true | String | (optional) - sets the timeout [in seconds] for voice browsers (default: "10").
(see haw:a tag) |