AT+CHLD=2 responds +CME ERROR 30

Incoming voice call, auto-answered:

So it’s not documented as a response to AT+CHLD

Clearly, there is network service - because a call is up!

So what does this really mean?

I get the same on pre-pay SIMs from Vodafone, Orange, and O2 (haven’t tried T-Mobile yet) - all UK.

I have now - the behaviour on T-Mobile is the same.

However, on Virgin (which is an MVNO using T-Mobile) the hold operation does work successfuly, and I can successfully dial a second call; but attempting to conference the 3 parties together (AT+CHLD=3) now fails

The problem doesn’t seem to be in the Sierra Wireless stuff - I get similar results if I try it on my phone.

I guess it’s because I’m using pre-pay SIMs, and the networks don’t provision this on pre-pay?

I still think Sierra Wireless is giving the wrong error message, though…

It means that this particular network service (Multiparty) is not available - it’s not saying that there is no service at all!

This should at least be more cleary documented, and preferable a distinct error code.

Yes - on the networks that support it at all, it’s only available with a contract.

All of the UK networks’ Customer Service (sic) lines have been utterly hopeless on this - continually giving advice that was unhelpful at best, or just plain wrong! :angry:

The summary seems to be:

Vodafone: Supported on Contract only, needs a call to Customer Service to enable it;
Orange: Possibly supported on Contract only (unclear);
T-Mobile: Not supported at all;
O2: Not supported at all.