18.1.3.6. ECDSA certificates 
Starting with OpenScape 4000 V11, you can use SPE certificates generated with ECDSA
Signature Algorithm (also known as "ECDSA certificates") for OpenScape 4000 SoftGate
and STMIX/STMIY, for SIP and HFA TLS signalling.
For H.323 trunking on OpenScape 4000 SoftGate and STMIX/STMIY, ECDSA certificates
are
not supported. In this case, traditional RSA certificates must be used.
HG3500 STMI2/4 boards do not support ECDSA certificates. In this case, traditional
RSA certificates must be used.
ECDSA has the following advantages over RSA:
- ECDSA provides a significantly lower output length for the same security level as RSA. For example, a 3072-bit RSA signature provides the same level of security as a 256-bit ECDSA signature.
- ECDSA runs faster than RSA.
- ECDSA requires significantly less memory than RSA.
However, you must ensure that the communication partner (e.g. the connected HFA or
SIP phones, or a trunking partner like OpenScape Voice or OpenScape SBC) supports
ECDSA certificates.
For more information, please refer to the Release Note.