What's the cheapest and easiest way for my web service to send and receive SMS text messages using shortcodes?

You have a few options for sending SMS through short codes. Below are two options. Note: all prices are for US Short Codes Option 1: Using a Shared Short CodeThe cheapest way is to broadcast your SMS is via a shared Short Code. Since shared short codes are not subject to rental fees, you only pay for usage. The approval process is faster, however, you can only use a set of pre-approved templates for SMS. See our FAQ for more info: http://plivo.com/faq/shortcode/what-is-dedicated-vs-shared-short-codes/ Here are Plivo's prices for usage under 5M SMS per month in the US: $0.0050 per SMS inbound: 100K SMS = $500 $0.0065 per SMS outbound: 100K SMS = $650 See the entire price break down here: http://plivo.com/sms-api/shortcode/ Option 2: Using a Dedicated Short CodeDedicated Short Codes are more expensive because you have exclusive use over your short code and you have the option of picking your own digits (aka Vanity Short codes). Dedicated short codes are subject to rental fees which includes includes hosting, short code rental, and carrier charges: Random Short Code: $2,700 per 3 months + $500 setup fee Vanity short Code: $4,200 per 3 months + $500 setup fee See our FAQ for more info: http://plivo.com/faq/shortcode/what-are-random-vs-vanity-short-codes/ For volume lower than 5M, we offer: $0.0050 per SMS inbound: 100K SMS = $500 $0.0065 per SMS outbound: 100K SMS = $650 Sign up before March 31st, 2014, we will deduct $1000 off your first invoice. And 12 month rental subscriptions receive 3 months of rental free. Option 3: Using a Long Code Carrier regulations state that long codes should only be used for person-to-person (p2p) communication, so this option is not recommended if you are doing application-to-person (a2p) communication. See the entire comparison in our FAQ: http://plivo.com/faq/shortcode/what-is-the-difference-between-a-short-code-vs-a-long-code/ Below are our prices for long code SMS in the US: Send Outbound SMS starting at 0.65¢ per SMS Receive inbound SMS starting at 0.45¢ per SMS Buy numbers at $0.8 per month See all https://manage.plivo.com/pricing/#!sms See the entire price break down here: http://plivo.com/sms-api/shortcode/

I coined the phrase "macro aggregator" a few years ago. At mobileStorm we realized that each aggregator had their strengths and weaknesses (pricing, service, features, connectivity, latency etc..). We figured why not integrate into a few of them and then provide one API that would allow our clients to send off of an aggregator that met their needs. Plus with how long we have been sending SMS (we are 11 years old), and our large sending volumes we are able to get very good rates. This allows us to offer very low cost per message including unlimited plans. So essentially we aggregate aggregators, to offer our clients the best scenario with good pricing, hence the term "macro", but of course we are not an aggregator with direct connections. If you go to an aggregator directly we like Ericsson IPX and mBlox.

Since cheap/easy is somewhat case by case, here is a list of 50+ that you could potentially use. http://blog.mashape.com/list-of-50-sms-apis/

Long code are a cheaper alternatives to shortcodes With this Android App, you can setup your own long code yourself  and receive SMS sent directly to the long your number on your website automatically and instantly. https://play.google.com/store/apps/details?id=ng.cloudware.sms2server to send BulkSMS, you can send it using BulkSMS Gateway API, contact @http://CloudSms.com.ng to give you the best pricing for your volume.

I don't know if you solved your problem yet, but just thought I'd throw in my two cents. Since the latest answer, Twilio has announced short codes (http://www.twilio.com/sms/short-codes). I'd keep an eye on them if I were you.

Whenever I try to sign up for text alerts using a short code, I receive an error message from my carrier (sprint). Are most carriers currently blocking shortcode texting by default? If so, isn't that a major problem for sms marketers? Is there a way around this? perhaps using long codes such as what is apparently offering?

I offer the services of my company, Waterfall Mobile's Msgme Platform (http://www.msgme.com), as we have been powering short code SMS messaging for enterprise companies (assume you fall in this category given your volume) since 2005. We have tons of dedicated short codes under management, provide shared short code options and give you access to an intuitive suite of APIs (http://developer.msgme.com). One thing in particular you might one to have a look at: our Dynamic Content option. Dynamic Content (included in our free trial) allows you to use SMS to call a web service. Using this platform feature, we have built a ton of custom applications including dealer locators, coupon code generators, garage door openers, foreign language translators, etc. You can read a brief description of our dynamic content API here: http://www.msgme.com/c/DevDoc?page=dyncontent

Cheapest with short codes is definitely going to be a shared code. There are many providers out there who can provide a platform with a friendly UI and API. I'll try to cover a few of them below -- http://www.sumotext.com/ http://www.textmarks.com/ http://tatango.com/ http://www.mobilecommons.com/ http://www.mobilestorm.com/ http://www.recessmobile.com/ (shameless plug)

currently has a shortcode program in beta, so if you are interested in having your own dedicated shortcode I'd encourage you to apply.  When you apply the product team will be able to supply more info on pricing and message capacity (which I'm not allowed to talk about yet) We're working through applications now, you can submit here: http://www.twilio.com/sms/short-codes