UC540 Radom Choppy Voice issue

[technicalspares]

I have a customer with a UC540W-BRI-k9, which I installed several years ago. It uses ISDN for voice and an EFM connection for data. Everything has been relatively ok with this unit until the beginning of this week. After changing the IP addresses of the WAN, including relevant ACLs as I migrated from the EFM to a 50 over 100 fibre, the users have been experiencing random choppy inbound voice issues. These are random with some calls being ok and others very badly affected.

Any help or guidance would be very much appreciated. All the normal QoS information seems to relate to SIP trunks and issues regarding the WAN. As this is using ISDN for the voice, I am at a loss to know what the issue is.

Regards Peter

[Aaron O'Hare]

Is the voice traffic running over the fibre link? If so does the carrier have CoS on that link?

If not you may want to look at your control plane and prioritize voice traffic at  the control plane if you have significantly increased bandwidth.

-AO

[technicalspares]

No the voice continues to use the ISDN and the new fibre connection being still only for data at present. Please can you elaborate on the prioritization of voice traffic at the control plane?

Regards Peter