10.55.3. Restrictions 
- In the case of MFC lines, no provision is made for step by step dialing. The system can be configured to prevent transit DID traffic from MFC lines from occuring on a step by step dialing route.
- A maximum of 22 digits can be transmitted.
- ANATE with DTMF is not supported
- Step by step dialing from functional S0 terminals is not supported.
- Step by step dialing is only possible for the Voice service.
- Step by step dialing is only supported by special ISDN exchanges due to premature B-channel through-connections. The LM44573 must be active in the EWSD exchange.
- The ECMA protocol cannot transfer any SETUP without Called Party Number (see Section 145.4.3, "Outdial Rule").
- Step by step dialing is not applicable for the US market.