PCM E1 DID limit for one number

[morio]

Hi guy's. need some help again. im having a client with PCM E1 DID and DOD. the DID tg 90 has 15 pcm boards configured. that 450 channels for DID. now i have an IVR connect to the system via T2 trunk group 120 and it has 120 channels.
the DID number to the IVR will use tg 90 and rout the call to tg 120. it works fine. but my problem is that when the IVR tg 120, has heavy traffic during a certain time all 120 channels in the IVR tg 120 becomes busy. this is normal as well. but unfortunately during this heavy traffic time all the channels in DID tg 90 becomes busy. we are not able to call any other DID using this trunk group.
the systems specs are as follows.

PBX type...... OXE crystal hardware.
release --- 11.2 Rl2.300.20.e
trunk group 90..... DID PCM with 450 channels (15 pcm boards)
trunk group 120 .... T2 ISDN with 120 channels (2NPRAE boards)

1 so why does the oxe accepts call on the IVR DID even though the routing tg 120 is fully busy.
2 is there any way to limit in the DID tg, number of time slots or channels can be used for one particular DID number?

any information with this regard will be helpful.
thanks

[sadim]

Try to put a CCD pilot in front of DDI and use the CCD/Trunk limitation mechanism.

Regards