Why are text messages that I send from my mobile phone to other mobile
phones so unreliable? I routinely send messages to my wife that she
never receives, and vice versa. And when I use online services (like
Google SMS) which break their responses into multiple messages, I
often receive only 1 of 2, or 2 of 3 messages.

I use T-Mobile, on a Treo 600, in the SF Bay Area.

Greetings,

Although, its very rare for someone in most of the Europe and some
Asian countries to report such behavior but there can be many reasons
for this unreliable delivery.

0. Network Elements - The cellular infrastructure is US is not as good
as european and some of the asean countries. In US, service providers
run the cellular services on existing plain old telephony system
infra. There could be some loss in the gateways, network elements.

1. Network Congestion - Short Messages are to delivered by the service
providers on the best effort basis. So, when the network is congested,
usually the messages get delayed but some messages may get dropped.

2. Delivery Mechanism - SMS that you sent is firstly saved on to some
queue. Then later retreived from the queue to send to the destination
network. This is called Store and Forward mode. If the SMSC
implementation is not efficient, some messages can go wary.

3. Message Expiry - Whenever you send a short message, usually you can
set the expiry time for the message using your phone settings (i am
sure about nokia phones). Lets say you set the message expiry to be 1
hour. Somehow, your wife's phone was switched off for 1 hour. The SMS
center will keep trying to deliver the message for 1 hour but as the
phone was off, lastly the message will be dropped.

You can test if your message is getting delivered or not by by
explicitly setting the Delivery Reports to ON. By the way, some
providers may not send the delivery reports back to you.

Hope this helps.
Navjot Singh

gcoladon, 

can i post this as answer if this reply satisfies you?

regards
Navjot Singh

Navjot-singh,
Only GA-Researchers whose names appear in blue can post official
"Answers" to questions.  I must say, your comment does seems like a
very professional answer.
I have to say "seems" because I know way too little about the subject
to offer a qualified judgement.
Regards, Myoarin

navjot_singh-g,

Thanks for your thoughtful answer. I wish I had a way to tip you a few
bucks for your effort, but I don't believe Google Answers has any way
for me to do that.

Warm regards,
Greg