Aastra 9617 Online User's Manual page 389

Note: If the Long Distance Ringing service is available in
your area, long distance calls will be sent to the Fax
Switch peripheral. If this is the case, do not use the Fax
Switch feature.
When the Fax Switch peripheral is idle, line 2 of the 9617
terminal can be used as a normal line. When the Fax
Switch peripheral is in use, the line 2 indicator light is on.
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