A UUS3 request is only accepted if the COT parameter UUS3 is set. If not, the request is rejected according to protocol.

Provided, the COT number 37 is set for the corresponding trunk:

CHA-COT:37,COTADD,UUS3;

The COT parameter ETSC can be used to define a virtual network limitation for proprietary UU messages (e.g. CMI, NW-CHESE, ...). Where the COT parameter ETSC is set, only UU information requested according to the ETSI protocol is transmitted .

CHA-COT:37,COTADD,ETSC;

The service UUS3 can only be activated by the calling party ( A station). If the COT parameter USBT is set, UUS3 can also be activated (network option) by the called party (B station).

CHA-COT:37,COTADD,USBT;

With UUS3, a station can transmit a limited data quantity transparently to the call partner. If the predefined data quantity is exceeded by one of the two parties and if the COT parameter USCC is set, the transmitting party receives a Congestion Control message. It informs the sending party that no further UU information will be accepted or transmitted. After a timeout (network option) the limited transmission of UU information is allowed again. This information is also signalled with a Congestion Control message.

If the COT parameter USCC is not set, the check of the data quantity as described above is prevented and an unlimited quantity of UU information can be transmitted (important for proprietary features such as CMI, NW CHESE, ...).

CHA-COT:37,COTADD,USCC;

If the COT parameter USCD is set, a UUS request is not forwarded to the forwarding destination.

CHA-COT:37,COTADD,USCD;

A defined maximum number of UU information messages (UUSCCX ) per time unit (UUS3T2) is available for each station with the UUS3 classmark. Regardless of whether or not the stock was used, the remaining stock is increased by a defined quantity (UUSCCY) after a certain time interval (UUS3T2), until the original maximum number (UUSCCX) is reached. In this way, the user is provided with a clearly defined bandwidth..

Provided, the corresponding trunk is a digital trunk with S2 interface (S2COD) in slot 1-2-115-1 and B channel group 1 has been configured (default value UUSCCX=16, UUSCCY=8):

CHA-TDCSU: DEV=S2COD, PEN=1-2-115-1, BCGR=1, UUSCCX=10;
 
CHA-TDCSU: DEV=S2COD, PEN=1-2-115-1, BCGR=1, UUSCCY= 5;

The timer UUS3T1 defines the maximum waiting time of the network side for an answer to a sent UUS request. If the timer expires before an answer is received, the service is released according to protocol.

CHA-CTIME:TYPESWU=CPTIME,UUS3T1=10;

The timer UUS3T3 defines the maximum waiting time of the user side for an answer to a sent UUS request. If the timer expires before an answer is received, the service is released according to protocol.

CHA-CTIME:TYPESWU=CPTIME,UUS3T3=10;

Every station with UUS3 classmark is assigned a certain maximum number of UU information messages per time unit which is defined by the timer UUS3T2.

CHA-CTIME:TYPESWU=CPTIME,UUS3T2=10;