*Ring* *Ring*

I figured out the trick to making calls with the GSM modem in the Treo 650, you just need to give it the subsidy unlock code with AT+CPIN="xxxxxxx". I also found something else interesting:

AT+CFUN=6
The handset is in Calibration Mode:
                                   

********Main Menu:********
                          
0  HELP                   
1  ARFCN arfcn
2  MODULATION 0=GMSK/1=8PSK
3  DACVAL FREQ_DAC_ZERO    
4  ALL_RAMPS           
5  RAMP_SELECT txlev(0-19)
6  AGC rxlev              
7  GSYS band step
8  START 0=norm/1=rach
9  STOP               
10 OAKWR addr val
11 ARMWR size addr val
12 ISPCS 1=TRUE       
13 OAKRD? addr 
14 ARMRD? size addr
15 RXLEV?          
16 GSYS? band index
17 MULTISLOT       
18 EN_AUTO_SIM 
19 L1 TEST     
20 EDGE/GPRS TEST 
21 TXDB_WRITE Row(0-7) [v0 v2 v3 ....v15]
22 CHANGEMODE mode :0=normal,1=cal,2=download

It doesn't respond to commands after that. I guess it may be expecting some binary protocol.

I'm still having the problem of after receiving *MRDY: 3 after powering on the radio the connection seems to freeze up. Messages are still received it's just outgoing keypresses that seem to be ignored. I found if I hold down a key long enough it'll eventually receive it and I can issue commands like that. Something strange must be going, perhaps there's some time window which it will receive in.

If I pull out the SIM the device will drop to MRDY: 5 and the AT console becomes usable again. Curious.

Update: Ah. I've found references to something called cyclic sleep mode. So perhaps the baseband goes to sleep for some cycles and then wakes up and can receive commands again.