GPRS, M55 and other questions

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JF Mezei - 27 Dec 2003 01:02 GMT

OK, I couldn't resist the offer from FIDO to get a M55 for $25, even if it
means that I am probably foregoing another upgrade for quite some time.

So, in a couple of weeks, I'll be moving from the 20th century to the 21st.
But I have a few questions since I would like to use my phone to connect to my server.

Is WAP worth investigating ? (the wapforum.com seems to want money to get the
specs of WAP, so muchj for the "open" in the open mobile alliance).

Does the M55 have a built-in HTTP web browser that can handle forms ? (for
instance, if I want to send some commands from a web page to my server). Or
would I need to provide WAP service ?

Is it correct to state that WAP can be served from any HTTP server (port 80,
http format requests, just that answers are in WAP format) ?

If I plug in my PDA to the M55 though the optional serial cable, is the PDA
configured for normal PPP handling ? (does it need to issue some ATDT command
with some dummy number, or does it just directly go into PPP mode as if
directly connected ?)

Is there a way for the server to translate the ip address assigned to the
phone to its phone number ?

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Nobody - 29 Dec 2003 08:53 GMT

> Is WAP worth investigating ? (the wapforum.com seems to want money to get the
> specs of WAP, so muchj for the "open" in the open mobile alliance).

So need to know the specs of WAP, really. WML is a very easy language to
learn.

> Does the M55 have a built-in HTTP web browser that can handle forms ? (for
> instance, if I want to send some commands from a web page to my server). Or
> would I need to provide WAP service ?

No low-end phone will support HTML rendering, it's not powerful enough,
especially since HTML is an error forgiving language. So you'll need to do
your stuff in WAP, but it's easy.

> Is it correct to state that WAP can be served from any HTTP server (port 80,
> http format requests, just that answers are in WAP format) ?

Yes. You simply need to write your file in WML and add the necessary MIME
types in your .htaccess or in the server's configuration.

WML is similar to HTML and XHTML, it's however stricter on the syntax. You
also have the power over some buttons to create functions. I believe you
live in Montreal, stop by InfoLivres+ on University, I'm pretty sure there
is still a few books left in the discount section for the excellent book
"WAP development using WML and WMLScript". I bought my copy for 10$.

> If I plug in my PDA to the M55 though the optional serial cable, is the PDA
> configured for normal PPP handling ? (does it need to issue some ATDT command
> with some dummy number, or does it just directly go into PPP mode as if
> directly connected ?)

I don't know specifically for the Siemens, but if it's the same as the Sony
Ericsson, you need to install a modem driver provided by the manufacturer of
the phone and establish a connection using a special dummy number.

> Is there a way for the server to translate the ip address assigned to the
> phone to its phone number ?

No, the GPRS connection is made through a NAT-type of proxy, the phone
doesn't get its own IP address.

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JF Mezei - 04 Jan 2004 11:22 GMT

> I don't know specifically for the Siemens, but if it's the same as the Sony
> Ericsson, you need to install a modem driver provided by the manufacturer of
> the phone and establish a connection using a special dummy number.

I don't run any microsoft junk. I don't want a driver, I need documentation on
what AT (or other ) commands needs to be sent to the phone, and whether the
PDA can then just assume standard dialup PPP negiotiations or whatever.

Nokia had learned very early on that proprietary stuff requiring special
drivers (such as for the 2100 and 6100 series phones) were a bad idea.

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JF Mezei - 03 Jan 2004 07:42 GMT

Foudn an interesting 3 page pdf document at:

>http://www.symbian.com/Developer/techlib/papers/GPRS/GPRSFactsInternetApplicatio
nDeveloper_pt1.pdf

Almost all consumer GPRS service is behind a NAT firewall, which means that
the IP address given to your phone is "local" to the mobile network and one
cannot establish a TCPIP call from the outside to your handset. There are some
networks whose NAT firewall is smart enough to have some specific
intelligence, for instance, allowing some UDP traffic back to the handset.

Another aspect is that multiple sessions can be established at the same time.
But you need a handset that does support multiple sessions, otherwise you need
to disconnect one session (for instance WAP or MMS) before you start a new session.

Still haven't found much about interfacing a laptop/pda to the phone (what
sort of protocol exists).

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