CUCM 12.5, 8841 phones transfer issue

[Jerrytech1]

CUCM 12.5, 8841 phones transfer issue

Calls transferred are losing audio volume. Each transfer results in more audio loss until you can't hear at all.

As soon as you hit the transfer key you hear it decrease. We have many buildings/locations but this issue is isolated to one location only.

[Nithin Eluvathingal]

It’s a strange issue, is this happen for just one phone or all phones in that location. 

all phones are on same firmware version? May be TAC support would be required.

[Jerrytech1]

All 8841 phones have the issue. The 3905 phones are not affected.