Frequent channel reset


I am stucked with a nasty PRI problem for 2 weeks now and will appreciate if I could get some help from here. The problem is that my zaptel.conf and zapata.conf have been working with one PRI line but it is not working with another PRI. We could easily blame it to the PRI line quality itself, but the fact is that the PRI line has been working fine with at least 2 PBXes without experiencing channel reset or call drop problem. From the asterisk console output, when calls are dropped, there is associated alarm detected.

I would like to know the following:

(1) After detecting an alarm, does the ISDN spec. specifies that all channels must be resetted or this is just an implementation choice which asterisk has made ?

Should asterisk reset the line after detecting the alarm and caused all calls being drop?

(2)I have a pri monitor ( ISDN tester) that sniffs the PRI line, I found that whenever the dropping calls problem happens, the monitor print out “RDI Begin … SAMBE ,RESTART, RESTART ACK… RDI end”.

Does anyone knows what is RDI other than what stated in the monitor’s manual as “Remote Defect Detect” and what causes it.

Attached is the PRI intense debug file.
Any pointer or help given is greatly appreciated !