@Crossunder, very interesting information. How do you solve the intercom issue on the 737? I know my company is right now in discussions with Boeing about a speech-activated intercom system as it is common in every SEP nowadays but is currently unavailable from boeing. Do you use a third party installation? And if so, which one?
Remember, though, that you have to have a service letter for the a/c and an official approval from the regulatory agency for EACH aircraft and EACH headset (which have to be registered with the tech dept. with its own serial number). Your company will have to apply for both.
That of course depends on local regulation and approved company manuals, in our outfit everybody has to use its own headset on the boeing fleet as the company currently does not provide any. We have the approval to use any kind of headset we want although TSO'd ones are preferred, but not required. That will most probably change though due to local worker safety regulation and the company will be forced to provide headsets of a pretty high minimum standard, therefore the talks about a real intercom system.