Do I understand right: you are trying to establish a CS data connection from
the GPRS module to another GSM phone? If you are calling the mobile number
(not *99#), you are not using GPRS but your GPRS module most likely supports
CS data too.

When the other phone rings, how do you actually answer it? The phone number
you are dialling should not be the voice call number of the other phone
(again assuming the other phone was a GSM phone) but you should dial an
incoming data call number. If you don't have one, you may not have
subscribed for mobile terminated data calls.

The other end should have a true PSTN modem or a GSM modem answering for a
data call, otherwise you do not get any data connection and no "connect" at
the dialling end.

A few more details about your setup would be useful, and comments if the
above assumptions were right or wrong.

I presume you don't imagine that you're able to establish a GPRS
session with the other mobile.

As you're probably aware, a voice call is of no use to you for
attempting to pass data to or from a mobile.  Because a data
call has OTA (over-the-air) characteristics incompatible with
those of voice calls, when establishing a CS (circuit switched)
data call you must tell all entities involved that you want to
make a data call.

When dialing mobile-to-mobile, you must do two things to achieve
this.

Firstly, you must make the OTA circuit from your mobile to your
network a data call.  You're probably already doing this, as
you'd need to append a semi-colon to the end of the "ATD"
command (after the number) if you wanted to make a voice call
using "ATD".

Secondly, and independently, you need to specify that the OTA
leg from the called party's network to their mobile is also a
data call.  You do this by calling their _data_ number, not
their voice number.  Inevitably, the owner of that number will
need to pay extra for this additional service (the second, data
number for the SIM).  Unfortunately, not all carriers offer
data calls, either for the making or the receiving, especially
for pre-paid services.  And those who do may also charge extra
for the privilege of being able to make data calls (separately
from the ability to receive them).

We need to know that you've taken the above into account before
we look for other possible causes of the failed connection.

Having said all that, there's a remote possibility that you can
unexpectedly manipulate your way through these obstacles by
simply asking for an ISDN (V.110) connection and dialing a
voice number.  So

       AT+CBST=71

is always worth a try prior to dialing.

John

Try to end with a ";"
ATD "number" ;
/BÖ