I'm new to IPT and am trying to get my head around a few things.
An SRST router is usually used to provide fail over for remote sites during WAN failure etc, however can it still be used effectively in a head office scenario?
Ie. if the voice router is configured with SRST, and the CM fails, am I right in thinking that the phones will fail over to the SRST device which is also the voice interface? And is there a loss of functionality such as Call Pickup, hunting groups etc.
Yes, you can certainly use the headoffice gateway as SRST. But also depends upon which gateway protocol you are using. Are you currently using H323 or MGCP?
I am not 100% sure about the features like Call Pickup and hunting groups. However you can certainly implement that in SRST mode