ah... i think now i know what you're talking about:

i have all the people whose calls i missed in my contacts. so doing the long-press thing opens the details and lets me choose between whatever i saved for them: not only different numbers i could try if i want to ring them back, but also the choice between GSM calls and SIP calls for example.

if, however, the number you find in the call log is not one of your contacts, you're lost if the phone initiates a GSM call but you want to call back via SIP. that's right. i didn't find a way to do this when i tried before.

so it pretty much depends on your lifestyle... my phone number isn't public so i couldn't get any calls from people i don't know. if i do, i don't answer because i know they either called the wrong number or want to sell me something.