MO-SMS will likely come after the SIP proxy is setup. One interesting this is, if you specify the full IP address with a number, you can send SIP Messages directly to other handsets. Stupid asterisk..can't handle SMS coming in from handsets :(

Wanna call me? 360-382-2103 ... I might answer, and you can leave a voicemail if you want too!

[/voip] permanent link

Fri, 30 Dec 2005

More fun with the SI-680H

After a lot of digging, I determined what "SIMPLE" messaging referred to. This is actually "SIP Message". Its supported by several handsets and pieces of software (like asterisk) to varying degrees. Currently, asterisk does not properly support reception of text messages, and can only transmit text messages to a handset during calls. This makes text messaging difficult to implement. My definition of "text messaging" is the ability to transparently send SMS-like messages of 160 characters or greater to other handsets, and ultimately, other providers. Which, BTW, can be done economically -- more on this later.

Thankfully, there are several promising hacks to offer such a system on VoIP phones like the Senao SI-680H that offer both MO (Mobile Origination) and MT (Mobile Termination) features via SIP Message.

As an added benefit, SIMPLE/SIP Message is supported during a call too on the handset. This is a very good thing.

Also, I have not been able to get the voicemail indicator to light (MWI) to show up on the SI-680H. I suspect that it does not support it. But then again, even one particular GSM carrier went without this for years, and simply used SMS notifications. Sounds pretty reasonable.

After I finish up a finalized asterisk configuration, which will include inbound/outbound dialing, voicemail, and activation system, it will be time for User Acceptance Testing (UAT). My hypothesis is that it will fail, but I plan on publishing some of the results...I suspect they will be interesting. People expect phone to work, cell phones are irrating, and i suspect that a VoIP phone with a UI designed by an engineer for an engineer will likely throw one heck of a wrench into the works. Maybe someone in Taiwan will read it and take a hint. Please give us good WiFi VoIP phones that end users like grandma can use!

[/voip] permanent link

SIP is Scary (Part 1)

There is nothing worse than an unregistered SIP phone. In this state, numerical dialing, as we know it, does not work. Dial 911 on an unregistered phone? HAH! sucker! Nothing happens. The entire concept of voice over IP is so abstract, there are many layers in the system (At Layer 7 or lower) that need to be put into place in order to permit voice traffic.

VoIP is not circuit-switched. The piece that makes the call is not sitting at the bottom of the OSI like other conventional cellular systems. You can't just dial a random number from an unauthorized phone, and get routed to 911, activation, or told that you are not permitted to make calls. Combinding VoIP with WiFi also introduces a number of new problems.

Lets go through the sequence of an average WiFi VoIP phone as it goes through all sorts of hoops to become a telephone. I will include basic flow and state machines in the same diagram. We will learn how complex the process is, what the breakdown points are, whats wrong with the state of WiFi VoIP today, and maybe some solutions to fix this problem.

Look at this giant state machine, and you can see why a simple concept as WiFi VoIP can be a very challenging ordeal. Being able to properly identify where a breakdown is taking place is absolutely critical in a WiFi VoIP network.

WiFi VoIP State Machine:

Here is more detail on all the processes involved:

Currently, on WiFi VoIP SIP phones today, dialing 911 (or any other emergency/activation/etc number) before State 7 results in no action. This probably goes for just about any other SIP phone out today. I propose the following framework or best practices for WiFi VoIP handling of emergency calls. Handset designers should probably consider incorporating some of these features. This will become more and more important as the FCC pushes E911 requirements on VoIP data networks.

Quick Draft - Best Practices for handling Emergency Calls

If "911" is entered into a (WiFi) VoIP handset, and handset is not registered properly, the following attempts should be made:

• Use pre-defined IP suffix existing in SIP phone config to place SIP call directly to proxy/gateway. IE: suffix is @10.1.1.2, so: 911@10.1.1.2

• If handset is associated but is not assigned an IP address, handset should contain a pre-defined emergency static address, range, or make use of auto config address to establish the SIP session to the emergency number at the specified emergency gateway.

• If handset does not have WiFi association, I am uncertain what the best effort attempt should be..

Handset should originate useful information that would aid in the location of the particular handset in order to meet E911 standards. Location information would be items like:

• Current SSID
• Current BSSID
• RSSI/Signal strength of current association
• Quick scan for all BSSID's within an SSID (ie: all seen AP's for a given SSID), and RSSI/signal strength to aid in trangulation
• Quick scan of everything near by, including SSIDs, BSSIDs, and associated RSSI/signal strength
• Identity information like username, etc.
• GPS location from internal GPS receiver

[/voip] permanent link

Thu, 29 Dec 2005

Senao SI-680H Review

The Senao SI-680H is a WiFi VoIP handset which resembles a Nokia 3300/8200 in terms of design, functionality, and feature set. It has a candybar form factor, numeric key pad, and several soft keys.

The feature set is very basic. It provides voice dialing and text messaging functionality. It also supports vibrate, several ringer presets, and various profiles similar to the 8200 line.

I could write a lot more fluff about this phone, but frankly we don't really care. We all know how a phone is supposed to work, and we all know the intent of this product. What we are interested in is the user experience -- and more importantly -- if I put this next to a Nokia 8260, would the user experience be transparent.

There are a few bugs in the current version of firmware:

displays

And some bothersome UI/execution issues:

Conclusion

A pretty good stab at WiFi VoIP, especially since a lot of fundamental issues have been addressed well in this handset compared to more unfavorable units *cough*Zyxel*cough*. Being able to roam seamlessly across a wireless network is absolutely important -- and it does it quite well. Better than most laptops on a WiFi network could. There was very little noticable drop out during handovers. This is with the G.711 codec!

Audio quality was also outstanding. While G.711 on the 680 blows my $400 CDMA phone out of the water, G.723 still sounded remarkably clearer. After calling several other numbers with my VoIP phone -- both circuit and packet switched -- I was beginning to notice that there are certainly a lot of VoIP phones out there with absolutely awful audio quality. Some of them were just a little overmodulated or tin can sounding.

BUT -- that aside -- A little bit of customization is desired in order to make this handset more "carrier grade" and "user friendly". If I could disable/lock the provisioning menu on the handset, customize the startup image, and make the #/* keys work, and got rid of all the VoIP/SIP techno clutter, i'd probably give it a higher rating.

On the horizon is the SI-681H. This is a color version of the phone, with improved internals, and a more Nokia-like user interface. This phone also looks much more customizable. This phone has not been released from Senao yet, but as soon as it is, i might snag one.

[/voip] permanent link

Mon, 19 Dec 2005

WiFi VoIP - Take Two

So after a 3 month ordeal waiting for my Azatel WIP VoIP phone, including lost packages in the mail, a UPS shipment that never arrived with no tracking number, my CC was mysteriously credited the full amount. The vendor, Innertree Communications has not offered any explaination for this. I am guessing they were not able to fulfill this order.

I have, instead, selected a US vendor by the name of Defacto Wireless. I ordered another AZA-WIP and Senao SI-680H this time. -- As it turns out, Defacto Wireless does not have stock of this AZA-WIP either. I am not certain what the status is on this handset...maybe the supplier has stopped production?

As a refresher, the AZA-WIP is a color java VoIP phone, and the SI-680H is a simple B/W VoIP phone with text messaging functions.

I have found a couple other OEM VoIP phone outfits over the past few months, but they are all the same -- unresponsive and/or plauged with supply problems. Some handsets have been in "development" for over a year.

[/voip] permanent link

Wed, 14 Dec 2005

Fundraiser Complete!

I am happy to report the SeattleWireless fundraiser is complete. This is a significant milestone in SeattleWireless network deployment! While financing could potentially be our biggest hurdle for this project, there is a lot of other hard work ahead for some of the core SWN members on this project. I really believe in everybody on this project, and suspect that we will stay on target, meet deadlines, and finish this project as soon as possible.

According to the project plan, the expected completion date of the fundraiser was 12/15/2005. Most certainly, the financing round is an important milestone in any project--otherwise it just would not get off the ground. This puts us on target so far, but I won't get too much ahead of myself. There is still a long ways to go.

Expect the holiday season to put a damper on this project. While purchasing and provisioning of gear can work in parallel of aquiring a tower climber, expect no climbing until after the holiday season (aka, all the big stuff happens January).

There is actually a pretty well-defined completion date. This will be announced after we officially secure a tower climber, and after we can schedule a climb date with the tower owner (which A-Toys simply leases space from).

[/seattlewireless] permanent link