How can I define the GSM connection as send connection?

Prerequisite: Several phone numbers are configured for your desktop phone.

Open Menu – Settings – Telephony - Send Connections

A list of the internal parties (desktop phone, handsets, fax machine INT8 – where connected) is displayed.

• Select the internal parties that should be assigned a new send connection and press the display key OK.
• Select at each call or select a connection as the send connection.
• Press the display key Save to save the changes.

If you select Select at each call, the internal party can select which send connection is used to establish a connection every time he makes a call.