An interesting debate was started today during a new Callmanager Express install:
During lunch one of the junior engineers asked why anyone would use SIP firmware on the handsets instead of SCCP.
A member of our group suggested that the only reason he could think of was to do with call-transfer options available on each platform:
When setting up the Unified CME system the engineer has to select either blind or full-consult transfer mode and set it system wide. If you intend using SCCP handsets you’ll only get this option on softkey whereas with SIP image on same handsets you get both options on softkeys.
Now we agreed that most customers normally want consultative transfers (permanant blind transfer is just rude!) but what happens if you need to do a blind-transfer say to voicemail? Is going to SIP the only option?
CME Expert, Anthony Fear, came up with the answer :
“Setup the system up with full-consult transfers but when you need to do a blind transfer – hit ‘Transfer’ as normal, dial extension and when you hear ringing tone hit ‘Transfer’ again – Viola a blind transfer in SCCP!”
“Quite why Cisco don’t use the same ‘Xfer’ and ‘BlindXfer’ softkeys that you get in SIP Image is a mystery. But hey there you go!”
Apparently SIP firmware offers a ‘semi-blind transfer’ but no-one in the group knew exactly what this meant and so although this could be a legitimate reason to choose SIP over SCCP we decided it’s a pretty lame one!