When you get a call on your mobile, the duration of the dialing tone is 15s for most of the Belgian mobile providers before forwarding to voice mail. For some people this is too short, so here's a list how you can increase the dialing tone for the various Belgian mobile providers. Just enter the code and press the dial button to activate the new duration. In the examples I set the duration to 30s.
Proximus: **61*+32475151516*11*30# or **61*+32475151516**30#
Base: **61*+32486191933**30# or *61*+32486191933**30#
Apparently for Proximus you can only use this code if you have post-paid formula, with Pay-And-Go (pre-paid) numbers the codes don't work.