trunk busy on ring free during silence

[leo]

Hi,
Facing an issue where outputs from some voip to tdm converter are terminated on nddi ports.
On these trunks of nddi charging bca trunk group, its observed that when there is a ring back tone the trunk shows busy but when there is silence the trunk is seen as free.
How to adjudge this behavior in order to encounter it.

Many thanks,
LEO

[vad]

Not understand - ring back and silence, busy and free! During incoming call trunk some times busy/ some times free?
May be you have problem with ring signal? F.e. in our country ring - 1 sec ring 4 sec silence. If in this case convetrer will send f.e. 2 sec ring 8 sec silence - during ring and 5 sec after - trunk busy. Next 3 sec (during pause between ring - too long pause) - trunk free.

[leo]

Thanks Vad for your kind reply.
The interpretation from your side is correct.
Any way to manage the same.

Many Thanks,
LEO