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New Member

UC540 busy issue

I have recently installed a UC540 at a customers site.

The fault is half the calls between extensions and from external carrier goto busy when the phone is not in use. I have watched the ephone and it shows IDLE, yet the trace and tone returns busy!

I have attached a copy of the ccapi trace which cause 17 being returned.

I was running uc500-advipservicesk9-mz.151-2.T2, so I tried changing to uc500-advipservicesk9-mz.150-1.XA3a, but still have the same issue.

Have thier been issues with these boxes where this has occured before?

any help would be appreciated


Re: UC540 busy issue

Hi Ashley,

Initial thought are LAN issue - but are the phones plugged into the UC directly ?

Are the phones registered ?


New Member

Re: UC540 busy issue

Hey Adam,

The phones are plugged into a switch, which is plugged into another switch, which is in turn plugged into the UC500.

All phones are registered when this occurs


Re: UC540 busy issue


Please rule the LAN out by taking two phones and plugging in to the UC directly.

When you have a working phone <-> phone call, does this call stay up and work continuously without drops in media ?

Re: UC540 busy issue

Check to see you do not have two ephone-dns associted to that ephone which is busy for alternating calls.

Depending on when the system was built, there was an old bug in CCA 2.x that used to do this when mixing extension ranges with analog user mode phones.   Worth a check anyway.

New Member

Re: UC540 busy issue

There are no duplicate DNs. It happens to all phones whether you dial from another internal extension or from an external line and it happens randomly. You can get 2 or 3 calls through. Then 4 or 5 will be busy etc etc. Completely random

New Member

Re: UC540 busy issue

Steven was right,

I went through the config and found someone prior to me had partially configured the extensions, but not assigned them to a device.

Thanks for your time guys

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