9.4 Control GSM calls via the Contact Mobile App
The features described in this section apply only to GSM calls displayed in the Contact Mobile App. The general conference call feature for app calls is described in 9.3 Start a conference call .
Requirements:
*You are using a SIM card provided by Summa. Personal SIM cards are not supported. On dual-SIM devices, the GSM call must be made using the Summa SIM card linked to Contact Mobile.
*Your SIM card is linked to the Contact Mobile App via a SIM link. See also chapter 12.1 Linking the SIM card.
*The active GSM call is displayed in the Contact Mobile App.
To end a GSM call via the app
You can see an active GSM call in the app.
1 Tap the call banner to open the call screen.
2 Tap on the End call .
*The GSM call ends.
To put a GSM call on hold via the app
You can put a GSM call on hold and resume it via the Contact Mobile App. The call must have been put on hold via the app. If you put the call on hold using your device’s native phone app, you cannot resume it via the Contact Mobile App.
1 On the call screen, tap Hold .
*The call is put on hold, and the other party hears music on hold.
To add another participant to an active GSM call and start a conference call
During an active GSM call, you can use the Mobile App to add another participant and turn the call into a conference call. This is also possible if the second call was originally started via the Contact Desktop App.
1 Open the Contact Mobile app.
2 Tap the call banner to open the full call screen for the GSM call.
3 Tap on More .
*Select Conference.
4 Select the desired contact or enter the second participant’s phone number.
5 Start the second call.
6 Once the second participant has answered the call, tap Conference to merge the two calls.
*The original GSM call is extended to include the second participant and continues as a conference call.
 
The conference call feature for GSM calls is available only if the requirements for SIM Link and an active mobile subscription are met. Without these requirements, GSM calls are not displayed in the Contact Mobile App and cannot be extended to a conference call via the app.