Avaya G3 calls between offices dropping after 20 minutes

[techalum]

Hello everyone!
I am having issues between two offices. When dialing via extensions, the call drops after 20 minutes. One of the phone systems is in the US office, the other in the UK. I have tried dialing other offices from these locations such as Switzerland and South Africa and I do not have that problem. Has anyone run into this situation? I saw a small blurb of information explaining what short code is and disconnectin after 20 minutes. Am I headed in the right direction?
This is the information I found:
Example: Maximum Call Length
The character t can be used in dialing short codes to set the maximum allowed duration of a call. For example, the following short code will dial a number but then disconnect the call after 20 minutes (plus or minus a minute).

Short Code: 9N

Telephone Number: Nt(20)

Can someone help me with this?

Thanks!

 

[wilsontec]

Have you check the clock sync ?

 

[montyzummer]

This is an Ip Office short code and logic and would disconnect after 20 min but is not applicable to Definity , can you confirm what switch you have?

APSS (SME)
ACSS (SME)
ACSS (UC)