Calls and Conferences with a Grandstream Conference Phone
Review the different features you can use to handle 1-on-1 and conference calls using your GAC2570 conference phone.
Written by Val Campos
Updated at October 6th, 2025
Table of Contents
Place a Call
You can do one of the following to start a call:
-
Press the Call button to use the Dial screen to call a phone number or extension number.
- If there is a Missed Call notification, tap the Call icon to return their call.
- Tap the Contacts button to call someone using a contact you have created for them.
- Tap the History button to find a previous caller to speak with.
The Dial Screen
On the Dial screen, you can dial someone's phone number or extension number to speak with them.
If you are calling multiple people, you can dial and select multiple numbers.
Once you dial someone's number, tap one of the following buttons to start a call:
- Create Conference - Start a conference call with the number dialed.
- Single Call - Place a 1-on-1 call to this number.
Answer a Call
When there is an incoming call for your phone, there are multiple ways to answer:
If you are already on a call, a Ringing… message will appear that shows the caller ID of the additional caller. You can press one of the following to answer the call:
- Tap then Answer option to accept the call as a 1-on-1 call.
✔ Doing so will answer the call as a 1-on-1 call with normal call controls for handling the call.
- Tap then Join Conf option to start a conference call or add this caller into an existing conference call.
✔ Doing so will answer the call as a conference call where you can tap the Add button to add more participants and use the call controls to handle the conference call.
If you do not want to answer the call, you can either…
- Press the Reject button to dismiss the call.
- Press the No ringing option to have the call silently ring.
Host Conference Calls
One of the main purposes for your conference phone will most likely be hosting conference calls. There are three different ways you can start a new conference call.
On the Dial Screen
If you are not yet in an active call, you can start a conference call with multiple people from the Dial screen.
1. Tap the Call button.
2. Dial and select the people you want to add to a conference call.
3. Tap the Create Conference button.
During an Active Call
If you are already on a call,
The Conference Control App
To start an impromptu conference call with the Conference Control app, you can do the following:
1. Press the Call button on the main Meeting Control screen.
2. On the Dial screen, enter the phone number or extension number of a person to invite to the meeting.
3. Enter the phone numbers or extension numbers of more people to add to the call.
4. Press either of the following buttons to start the call:
• Start Audio Call 
- Initiate a conference call that uses only audio.
• Start Video Call 
- Initiate a conference call that uses both audio and video.
Conference Call Controls
| Feature | Description |
|---|---|
| Mute | To mute your microphone during the call, tap the Mute option. When you are ready to speak again, tap Unmute. |
| Start Recording | To record just the audio of the conference call, tap the Start Recording option to start recording audio. If you are recording a snippet, tap Stop Recording to stop recording the call. |
| Keypad | If you need to interact with a menu or dial a code, tap Keypad to pull up a dial pad. |
| Hold | To place the whole conference call on hold, tap the Hold option. Once the conference is ready to be resumed, tap Unhold. |
To view more of the different features you can use to handle an active conference call, tap the Down arrow 
above the End Call button.
Doing so will show five more features: Participants, Unlock/Lock, Call Details, Programmable Key, and New Call. 
| Feature | Description |
|---|---|
| Participants | View the participants of your conference in a list along with controls for managing their participation in the call.
|
| Unlock/Lock | Once a conference call has started, you can unlock/lock the call to allow/disallow more participants from joining. |
| Call Details |
View different call quality metrics about the call, such as packet loss.
|
| Programmable Key |
Open the Programmable Keys menu to tap a BLF button you want to place a separate call to.
|
| New Call | Start a separate call with someone outside of this conference call. |
Manage Participants
When you tap a participant in the call, you will have options to use to manage that person's participation in the conference call.
- Mute: Mute this participant’s microphone. Muting a participant can be helpful if they are contributing to unnecessary background noise.
- Hold: Place a single participant on hold if needed.
- Remove: Kick or remove a participant from the conference call.
Talking 1-on-1
Once the person you are calling to answers your call, you will see features on the right that you can use to handle the call.
To view all of the different features you can use to handle an active call, tap the Down arrow above the End Call button.
Doing so will show four more features: Transfer, Call Details, Programmable Key, and New Call. 
| Feature | Description |
|---|---|
| Transfer | Transfer a call to another person using a blind or attended transfer. |
| Call Details |
View different call quality metrics about the call, such as packet loss.
|
| Programmable Key |
Open the Programmable Keys menu to tap a BLF button you want to place a separate call to.
|
| New Call | Start a separate call with someone outside of this call. |
Mute Yourself
Hold and Resume Calls
You can place an active call on hold and resume the call when you are ready. When you place a call on hold, the caller will be listening to music until their call is resumed.
Place a Call on Hold
While speaking with someone, you can place their call on hold by tapping the Hold button.
Any time you initiate an action (e.g., transferring or conferencing), the call you were on before will automatically be put on hold.
Swap Between Held Calls
While handling multiple calls or starting a transfer, you may need to swap to another call. To swap between held calls…
-
Put the current caller on hold.
- Tap the Number of Calls
button on the left to select a different held call.
-
Select the call you want to swap to from the list that appears.
- Tap the Unhold button to resume that call.
Resume a Call
If you are ready to begin speaking with a caller you placed on hold, you can resume that call by tapping the Unhold button.
Transfer a Call
While handling a call, it may be necessary to pass the phone call along to a user, call queue, or an external phone number. This can be done through transferring.
While handling a call on your Grandstream conference phone, there are three different methods of transferring that can be utilized depending on how exactly the call needs to be transferred and handled:
- Blind Transfer - Transfer a call directly to another person without talking to that second person. This is method of transferring is also referred to as a “cold” or "unassisted" transfer.
- Attended Transfer - Speak with the person being transferred to before completely transferring the call. This method of transferring is also referred to as a “warm” or “assisted” transfer.
- Voicemail Transfer - Transfer a caller directly to a general mailbox or the voicemailbox of another user.
Use the module below to view step-by-step instructions about how you can perform these different transfers:
Blind Transfer
When you use a blind transfer, you transfer a call without speaking to the party that the call will be transferred to. The person receiving the transfer will need to answer the transferred call.
To perform a blind transfer…
1. While on an active call, tap the down arrow to show the additional active call features.
2. Tap the Transfer option.
Note: The caller will be placed on hold automatically where they will listen to music on hold.
3. On the Dial screen, dial the person's extension number or phone number.
4. Make sure the Transfer Mode dropdown on the left has Blind Transfer selected.
5. Tap the Transfer button.
Attended Transfer
Perform an attended transfer if you want to talk to the person receiving the transfer. This can be a great way to check that the person being transferred to is actually ready to receive a transfer. If the second person answers your call and an attended transfer is completed, the caller will be directly connected to the second person without the need for them to answer the call.
Quick Tip: If you decide you do not want to talk to the person you are transferring to, you can perform a semi-attended transfer. To do so, you can tap the Transfer now option while the call is still ringing.
1. While on an active call, tap the down arrow to show the additional active call features.
2. Tap the Transfer option.
3. On the Dial screen, dial the person's extension number or phone number.
4. Tap the Transfer Mode dropdown on the left.
5. In the Mode menu, select Attended.
6. Tap the Transfer button.
7. Wait for the second person to answer the call.
8. Talk to the second person as needed. When they are ready for the transfer, tap Transfer now.
If this person says they are not available for a transfer, tap Split to take the call out of transfer mode. 
End the call as needed.
Transfer to Voicemail
In some instances, a caller may need to reach out to a user that is not able to accept a transfer at the moment. If this is the case, the caller can instead be transferred to a user's voicemailbox to leave a message.
To transfer a caller to a user's voicemailbox…
1. While on an active call, tap the down arrow to show the additional active call features.
2. Tap the Transfer option.
Note: The caller will be placed on hold automatically where they will listen to music on hold.
3. On the Dial screen, dial 03 and the user's extension number.
4. Make sure the Transfer Mode dropdown on the left has Blind Transfer selected.
5. Tap the Transfer button.
✔ The caller will now be listening to the user's voicemail greeting. Once they are prompted, they can leave a voicemail for that user.
Use the Keypad for Interacting with Menus
- Tap the Keypad option while on the call.
- Use the keypad that appears as needed.
