[kesslerdesign]

at+csca?
+CSCA: "",129

OK

That's what I get with my 6210 (v5.27 and also previous sw) instead of the smscenter-number which can be read with 51xx, 61xx and others like that. Playing around with CRES helps nothing.

So how do I get the (default) smscenter via AT out of a 6210?

[pautamo]

Does the phone contain the SC number in the message settings?
You can also set the SC number yourself: AT+CSCA="+3478987987",145.
Then you can try to save the setting with AT+CSAS=1. There can be
slight differences in how the AT-commands work in different
phonemodels.
BR
M, Forum Nokia

[pautamo]

You can send the PDU without the SC address just put two zeroes
in front of the PDU. I managed to send that kind of messages with
Nokia 6210 sw version 04.08. This works also for Text mode.
The SC address in this phone is fetched from the phone in sending phase, unless it is given in the AT+CSCA or in the PDU.
In newer models SC-address is fetched in the beginning of session to
at+csca and used from there after that.
at+cmgs=29
0011000C915354508191420000A71154747A0E4ACf41f4f29C9E769F4121
I hope this solves your problem, since I don't think there will be
anymore updates to Nokia 6210 sw.
BR
M, Forum Nokia