Blazor Helpers App Twilio: Discussion about using SMS


Discussion about using SMS to request confirmations from volunteers using SMS in the Helpers app.

As part of the Helpers app, as discussed in previous posts here, there is a requirement to send a message requesting confirmation by volunteers of there availability to to do the task they have volunteered for an up coming round of athletics competition. Helpers self-volunteer for specific jobs in a specific timeslot during the day. A simple Y or N response is required so that the athletics club knows in advance that all of the jobs that they are required to perform, as decreed by the athletics association, are covered. The intent is to send the messages to helpers 2 days before the day of competition.

The requirement is that the database is interrogated for activities on the day that have a non-null helper assigned and to send a customised message to eacj helper including the specific details of the task. Where a helper has volunteered for more than one task on a day, the information is merged into one message. The Y or N responses are processed upon return and interpreted as Yes or No and logged in the database against the specific activity. An Admin user can see these responses when viewing the activities for that day. Also, upon interpretation, that is forward to the Admin. This is optionally limited to just the No responses.

An email version of this mechanism was implemented. It was desired though that SMS be used as the carrier for all 3 messages: the request, the response and the on-forward of the yes or no. Note that the email mechanism did not go to waste. In registering, email was optional. In registering and for logging in, a name and mobile number are required. The name is what needs to be unique. Multiple helpers, say a family, can share the same mobile number. Where a helper does not have a mobile number, or doesn’t wish to divulge or to use it here, a default mobile number is used. If when sending a message to a helper the mobile number equals this number, then email is used. The emails make use of an existing Office365 account, rather than establishing a a mail service just for that purpose. This could be extended to use the athletic club’s website host’s email facility, which already exists. (A 2Do).

Twilio was used to implement the SMS mechanisms. This comes at cost but it does work. Some issues:

  • For test purposes, with a free trial account, the messages can only be to and from a US number.

  • There is a $US7 per month charge for a local assigned mobile number for sending and receiving app SMSs.

  • So development, here in Australia, did require an upfront outlay.

    • In getting the messaging to work, there were many errant messages at the start.

Another issue that I just resolved was that the first full use of this mechanism quickly used funds for the account the problem, as it turned out, was that the messages being sent to helpers were about 360 characters resulting in 3 segments being sent. That is, each sent message was costing 3x a single message. In these days of mobile plans with no limit on local SMS, we tend to forget that when we send an SMS of any length, we are actually sending several messages, which are seamlessly merged back into one at the helper’s end. The on-forwarded messages to Admin are well below the 160 character SMS limit and so they only cost one unit. Also, received messages cost substantially less than sent messages. Twilio costs are

  • $US7 per month for a locally assigned mobile number (Required)

  • $US0.055 per message segment

  • $US0.0075 per received message (None of our received messages were more than one segment, but segment multiples would probably apply).

These costs are not large but for a not-for-profit community sporting club they can mount up . For a corporate context theses charges would typically be minuscule compared to the fee for service they would apply. Alternatives to Twilio were not considered in the first roll-out of the app but are now under consideration. There are free SMS services (see below) but they probably cost when they need to integrated into an app via an API. Or they may require advertising with sent messages. Looking into options here as I have had an enquiry from another club about using the app. At he moment I have used my own cloud entitlements for hosting the app and covered the Twilio costs myself (until I seek reimbursement form the club). One alternative is to run the app a mobile’s web browser and generate text to be sent and a list of mobile numbers, both of which can be copied into an texting app on the phone. This though would require a non-customised message to be sent to helpers form an Admin user. The Admin would then need to manually forward all responses into the app. An alternative might be a separate Xamarin app of the phone that can directly access the database and generate all of the customised messages and send them. Manually handing of the response though would still be required. Have tried any of these yet but here are some sample Xamarin apps for sending SMS:

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