60
www.lairdtech.com
Laird Technologies
BTM510/511
Bluetooth
®
Multimedia Module
7. HFP (Hands-Free Profile)
The Hands-free profile (HFP) defines how two devices supporting HFP shall interact with each other on
a point-to-point basis. The use case for HFP is a hands-free unit that is connected wirelessly to an audio
gateway. The audio gateway is typically a cellular phone. The hands-free unit acts as audio input and
audio output of the cellular phone and allows to control typical telephony functions to be performed
without access to the actual phone.
A BTM5xx module is required to be controlled by a host processor using AT commands (hosted
operation mode). BTM5xx HFP implementation supports both Hands-free role and Audio gateway role.
An AT command beginning with AT+HF... indicates affiliation to Hands-free role of HFP.
An AT command beginning with AT+HFG…indicates affiliation to Audio Gateway role of HFP.
Version 1.5 of the hands-free profile is supported [5].
Table 3.28 below shows the feature requirements for this profile and the level of support on BTM5xx.
It is highly recommended to download the profile specification [5] in order to understand the procedures
related to a certain AT command. For quick navigation, references to [5] are given in this section which
follow the syntax:
#<Feature>_<Section>
With:
<Feature> = HFP feature no. in Table 3.28 and Table 3.1 of [5]
<Section> = Appropriate Section in [5]
Example: #3_4.12
feature no. = 3, section = 4.12
HFP Feature
Support in HF
Support in AG
Specification
BTM5xx
Specification
BTM5xx
1.
Connection management
M
Yes
M
Yes
2.
Phone status information
M
Yes
M
Yes
3.
Audio Connection handling
M
Yes
M
Yes
4
Accept an incoming voice call
M
Yes
M
Yes
5.
Reject an incoming voice call
M
Yes
O
Yes
6.
Terminate a call
M
Yes
M
Yes
7.
Audio Connection transfer during an ongoing call
M
Yes
M
Yes
8.
Place a call with a phone number supplied by the HF
O
Yes
M
Yes
9.
Place a call using memory dialing
O
Yes
M
Yes
10.
Place a call to the last number dialed
O
Yes
M
Yes
11.
Call waiting notification
O
Yes
M
Yes
12.
Three way calling
O
(2)
O
(2)
13.
Calling Line Identification (CLI)
O
Yes
M
Yes
14.
Echo cancellation (EC) and noise reduction (NR)
O
(5)
O
(5)
15.
Voice recognition activation
O
(5)
O
(5)
16.
Attach a Phone number to a voice tag
O
(5)
O
(5)
17.
Ability to transmit DTMF codes
O
(5)
M
(4)
18.
Remote audio volume control
O
(1)
O
(1)
19.
Respond and Hold
O
(2)
O
(2)
20.
Subscriber Number Information
O
Yes
M
Yes
21a. Enhanced Call Status
O
(2)
M
Yes
21b. Enhanced Call Controls
O
(2)
O
(2)
M: mandatory
O: optional
(1) support planned for future AT firmware release
(2) support planned for future AT firmware release, but with low priority
(3) not planned to be supported for future AT firmware
(4) service level signalization only
(5) support for service level signalization only planned for future AT firmware release
Table 3.28: Hands-free Profile supported features on BTM5xx
AT COMMAND SET
REFERENCE
