WordPress MU

I am looking for an SMS solution to modify my WP mu setup. Thinking out loud here... Maybe somebody could point out some existing plugins and other resources on which my solution can be based.
What I want is: All the subdomain Admins should be able to send bulk SMS to their subscribers (for stuff like announcements etc.)
I am not even sure what kind of infrastructure I need. Email to SMS will not work for me (not reliable).
I am thinking along the lines of having a plugin that pulls the subscriber list and displays it, along with an SMS text area below. SMSs are sent by selecting the users from the list (tickbox or select all) and pressing send...
Also, I need to be able to track how many SMS each subdomain is using up.

Guess an SMS gateway will be needed, but not sure how the subdomains will interface with the gateway? A simple text list of subscribers sent via E-mail to the gateway? Each subdomain will have a minimum of 50 and maximum of 1000 subscribers who have registered their cell phone numbers.

What I will end up needing:
1) A plugin to modify the Profile page so that a subscriber's cell phone number can be input- may be replace AIM, Yahoo, Jabber. Usernames and passwords are generated by the admin from the admin panel itself, so subscribers only need to update their profile with details like name, cell number etc.
There are some already out there, including a) Cimy, b) this one by Igor Olemskoi, c) WP User Manager
I don't think any of them work out of the box.

2) A plugin to display the SMS menu item and its contents, including fetching records from the database, displaying in rows (with a select tick box next to it), a text area (100 characters) where the SMS message can be typed in, and a send/cancel button. This plugin should also have the interface to send the list of cell numbers and the SMS message to the gateway (via E-mail?)

Please comment on this approach, any comments.
Thanks.......

The first thing you want to do is go and find an SMS gateway provider - there are a lot out there but the prices are different depending on the destination, how many messages you pre-buy and your estimated traffic.

Pick one that has a web API to allow you to send the messages and get confirmation of delivery (so you can relay this to your users).

Then it is a matter of interfacing it with WordPress MU - it should be straightforward if the SMS gateway has a decent API and documentation.

I've done this a long time ago (not with WordPress though) with a company called iTagg. They are based in the UK, but I wouldn't recommend them as I had a protracted run in with them when they pulled one of my clients short-codes with short notice because "he wasn't using them enough".

Thanks Cafespain!
When you say "Pick one that has a web API to allow you to send the messages and...", how do the subdomain admins send the messages? Are these gateways designed to accept bulk messages via Emails? I looked at some of them, and they all seem to want users to login to their server/site and fill out a form with cell numbers and the message. Is this standard practice, or am I looking at the bad providers? Google search is almost useless- the SERPs is stuffed with SEO optimized commercial sites.
Do you have a feel for what kind of time frame (hours) will be required for a project like this? I mean if I get it done using a developer.
Checked out iTagg- seems to be based on the concept of revenue generation via short codes...thanks for letting me know of these types. I am looking for straightforward SMS.

A good few SMS providers have both options. A lot try to sell the short-codes as revenue generation, but their primary business is bulk SMS (they have to have the infrastructure in place to send their own responses).
Have a look at providers such as:

http://www.bulksms.co.uk/w/solutions_http_to_sms.htm
http://www.mediaburst.co.uk/integrated_sms.cfm
http://www.redsms.co.uk/
http://www.clickatell.com/developers/php.php

You would have a plugin with a form interface as you described in the first post. The plugin would then interface behind the scenes with the SMS gateway (all the ones I linked to above have a Http gateway as well as email, but the http api is the way to go) and return the results.
The sub-domain users don't need to know who is sending the SMS messages on their behalf, only the admin (you) will have the provider details.

The timeframe depends on your required security needs. Are you going to allow your users to send as many SMS's as they want and when they want (could get costly), Do they have to buy credits from you beforehand?, Do you want to limit them to sending only every x hours? If the gateway has a limit on the number that can be sent per batch then you would have to build in a batching system, etc..

All in all your probably talking less than 5 hours work for the plugin, unless you want bells and whistles :)

Yes, my users (i.e. Admins of the subdomains) will send out the SMS to their subscribers. Each indivdual subdomain's Admin will send out these SMS (free at this time during the trial phase). Yes, could get very costly, but I will choose just 5 of these subdomains for the trial run. The SMSs will be far between, but when they do go out, there will be high traffic, with probably many subdomains trying to send out messages at the same time.

I have not fully worked out the financial aspects, just trying folks to use the service and get feedback.
If we decide eventually to let subdomain Admins buy credits, will setting up separate tracking for them going to be difficult? The API on the providers end will have to understand which subdomain it is coming from. I guess having the ability to track it from my WP mu Admin interface would be easy and an added plus...

I am going to talk to my partner and see which way to go, and also budget it.

One thing I didn't understand was the security aspect. When you said "The timeframe depends on your required security needs", I am assuming you meant throttling the SMS send rates to conserve credits- am I right? Are there any other security issues?
Thanks a bunch...

Yeah, Security wise it's just a matter of ensuring that only those you authorise can send the messages and then only however many you set and how often.

You can usually set a "from" identifier for the messages which would allow you to track via the gateway provider who sent which messsages, and would also be able to tally it with your MU interface records.

I'm not sure whether this thread is stil active. We are Text Marketer and have an sms gate api. Low cost and very reliable http://www.textmarketer.co.uk
http://www.textmarketer.co.uk/sms-gateway.htm