NO JOY Delay in hearing ring-tone

[LesD]

I have had a complaint from someone switching from an ISDN lines based switchboard ,that there is a 'long delay' before they hear 'ringing'.

Limited testing to an external number (PIAF system to PIAF system using VoIP trunks) actually shows that the target line starts ringing about a second before the calling extension actually hears ring-tone.

Is it possible to make the calling extension always hear a ring-tone as soon as dialling is finished? This would make everyone happy.