isdn call disconnections

[themizzz21]

Hello

A client has a uc520 that connects to the pstn via isdn service.
The installation worked without problem for more than 6 years.
The last four days users experience frequent disconnections during their conversations.
When the issue occurs the debug isdn q921 debug isdn q931 and debug isdn error messages are the following:
*Oct 12 16:16:17.353: ISDN BR0/1/0 Q921: User TX -> RRp sapi=0 tei=0 nr=7
*Oct 12 16:16:17.373: ISDN BR0/1/0 Q921: User RX <- RRp sapi=0 tei=0 nr=6
*Oct 12 16:16:17.373: ISDN BR0/1/0 Q921: User TX -> RRf sapi=0 tei=0 nr=7
*Oct 12 16:16:17.461: ISDN BR0/1/0 Q921: User RX <- RRf sapi=0 tei=0 nr=6
*Oct 12 16:16:21.085: ISDN BR0/1/0 Q921: User RX <- IDREM ri=0 ai=0
*Oct 12 16:16:21.085: ISDN BR0/1/0 SERROR: L2_Go: at bailout DLCB is NULL
L2: sapi 63 tei 127 ces 0 ev 0x3
*Oct 12 16:16:21.089: ISDN BR0/1/0 Q931: Ux_DLRelInd: DL_REL_IND received from L2

Is it telco's responsibility or is something wrong with the uc?

Thank you very much.

[acampbell · Accepted solution]

Hi,

See link

https://www.cisco.com/c/en/us/support/docs/dial-access/integrated-services-digital-networks-isdn-channel-associated-signaling-cas/5707-bri-layer2.html

You are receiving IDREM from the TELCO

IDREM

The ISDN switch has removed the TEI (ID) from the connection. The router must discard all exiting communication using that TEI.

Check to see if a new TEI is assigned at a later time. If not, contact the telco.

[themizzz21]

Hello,

i contacted telco to investigate the issue.

Thank you very much.