```
number is a necessary parameter (at least one parameter) for MT call on emulator
```
Yes, that's what we _expect_, but the source code tells me otherwise.  There is no clue that tells the reader, me, that these newly added lines enforce the rule "number is a necessary parameter".

By `<SP>`, I meant ASCII SPACE character.  When we type `gsm cancel <SP>` and hit ENTER, you get `<SP>\0` as `args`.  Then in line 1367, you have `params[0] = NULL`, line 1377 is skipped because `top_param == 0`, line 1381 you have `number = NULL`, .... at the end you have `amodem_add_inbound_call(client->modem, NULL, ...)` in line 1419, and please also trace down to _telephony/android_modem.c_:1160, `len  = strlen(number);`. Bang! Segmentation fault.