3Com NBX 100 Administrator's Manual page 247

The system verifies the account code against the list of valid account
codes.
On a phone with an LCD, an invalid account code shows the text
string
Unknown Account
On a phone without an LCD, an invalid account code plays the Feature
Error tone, and the call continues.
Unforced / Unverified Mode
Unforced / Unverified mode is similar to Unforced / Verified mode, but the
account code is not verified. The phone displays the account name if the
account code is valid and the call continues.
The account code and account name information is available in CDR.
Configuring Enforcement and Verification
To manage account code usage on the NBX system, follow the
instructions listed in this section.
To allow or disallow verification of outgoing calls:
1 Log in to the NBX NetSet utility as Administrator.
2 Go to User Information > Account Codes.
3 Click on the appropriate account code (or create a new one before
proceeding).
4 Check or uncheck the Enforce account codes verification check box,
as appropriate.
5 Click Apply.
To enforce or relax the need for an account code:
1 Log in to the NBX NetSet utility as Administrator.
2 Go to User Information > CoS.
3 Select the appropriate CoS group name.
4 Click Modify.
5 Locate the appropriate Class of Service (such as International or Long
Distance), then check or uncheck the corresponding box marked Force
Acct Code.
, and the call continues.
Account Codes 247