Quote:
Originally Posted by jmseight
Hi All,
I read in the forum that there are some interest in making SIP client on Kindle, like port of sjphone. Since the K3 has mic and speaker, is this feasible?
Has someone done it already?
This would be an excellent hack.
Thanks,
James
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Your info block reads "Kindle 3G" and your question above mentions the "K3 with mic and speaker" so I think my machine is similar to yours.
A Kindle (3) Keyboard with 3G modem/radio.
Session Initiation Protocol (SIP) protocol is an Application Layer protocol which may be used for many purposes, but since you mention a SIP phone application....
First related question: Can we make a cell phone call over the built-in 3G modem/radio?
Fast answer: No.
The AnyData modem/radio as used in the K3-Keyboard model does not have the voice services included in its firmware.
Can the modem/radio firmware be changed?
Fast answer: Not likely.
The "second ARM" of the K3-Keyboard uses a cryptographically signed firmware image. It is unlikely that this can be "broken" or "worked around".
SIP being an application level protocol does not depend on the transport layer it is riding on, so...
How about SIP/VoIP over the 3G data channel?
Short answer: Not practical.
Technically possible but in practice, the traffic of the 3G data channel is under the control of the provider and the provider's client (Amazon). These controls are highly automated and operate in real time.
So unless Amazon announces they will allow this as general use of the "Free 3G" it is probably just a waste of time to develop.
How about SIP/VoIP over the Wifi radio?
Short answer: N/A
no short answer for this one, sorry.
If you have access to a fast enough Wifi access point, then this could be made to work.
In fact, the Wifi communications of the K3-Keyboard can be faster than the data channel provided by the AnyData modem/radio.
Note that the majority of the "Free Wifi" access points provided by AT&T (and other carriers) will be too slow for decent quality VoIP.
Since your post mentioned a 'phone application, I answered that first, but there are other possibilities...
How about SIP/SMS?
The result would be a multipoint IM communications similar to a Jabber "Conference Room".
SIP/SMS over the 3G modem/radio:
Short answer: Possible but subject to provider and provider's client controls (see above).
This could be implemented over either the SMS channel or the Data channel provided by the AnyData modem/radio.
SIP/SMS over the Wifi:
Short answer: Possible and Practical.
SIP/<something else>
What else did you have in mind?
Maybe I can answer that question(s).
External ref:
http://www.sipknowledge.com/eBooks.htm
Other notes:
The SIM card can be changed to a provider account other than Amazon. In fact, Amazon will sell you a un-initialized, AT&T, SIM card for about $2.
SIM cards can hold multiple provider access point names, if my human memory serves, 16 of them. It may be possible to add access point names for accounts other than Amazon's account.
EDIT:
That last statement wasn't clear. Sorry.
The access point name(s) are read and written with modem "AT" commands. Any modem can do that, those commands are part of the ones required by the industry standards.
There is also a "locking" feature for "locking" a SIM card. The "may be possible" comes from my not being certain if the Amazon SIM card is cryptographically locked.
The AnyData modem/radio is a mini-PCIe card in the K3-keyboard. Easy to change out for another modem/radio that has different features (like the voice channel services).
Some (most?) of these use the same Qualcom (ARM) SoC and recognize nearly all of the same "AT" modem commands.