To join your Skype group call from a mobile or landline, your friends need to dial your Skype Number. You can then add them to the group call in Skype. You can have a group call with up to ten people (nine plus yourself).
If you're on a mobile with Skype installed, you can simply join the call by placing a Skype-to-Skype call to the group call's host from within the Skype application. If you're the call host, and one of the participants has Skype on their mobile, you can simply add them in the same manner.
To add a mobile or landline caller to a group call already in progress, click the More icon (+), then click Add people to this call in the incoming call window that appears. Note that adding someone via a mobile or landline will cost Skype Credit (or might be covered if you have an existing subscription).
You can also merge calls. If you click Answer to incoming calls or call contacts individually, you will see more than one ongoing call on your Recent tab. To merge calls simply drag and drop one call to the other.
In the example below, you’d click and drag Charlie Kent to James Cooper, Jiro Ishikawa.