If you are asking whether a SCCP phone can fail over to a SIP SRST instance on a gateway, the answer is no. If you have both SCCP and SIP phones you will need both SCCP and SIP SRST instances. Both SRST instances can run on the same router, though.
If you are asking if a SCCP phone registered to CUCM can have CUCM send a call through a gateway that happens to also be a SIP SRST gateway, the answer is that it should make no difference since it is CUCM and not the SCCP phone that signals out to the gateway.
And if your question is neither of these, can you ask again?
Maren
