14.6.4.1. Restrictions 
- Dialing with overlapping digits is not supported in OpenScape Voice (overlapping reception is supported).
- With a OpenScape 4000 - OpenScape Voice (Transit) - OpenScape 4000 scenario, the message waiting display is not routed via OpenScape Voice.
- HG 3500 does not support digit authentication.
- The payload partners can be defined with DMC in a HiPath 400/OpenScape 4000 network. A OpenScape 4000 cannot however send the payload directly to or receive it directly from OpenScape Voice partners. A hop always results on the HG 3500 module.
- If there are more than two partners configured for the HG 3500 (e.g. Proxy) and REGIP1 fails, REGIP2 remains registered until REGIP2 is no longer available. Automatic switchback to REGIP1 is not possible.