• How do I know if my text message was delivered?

    When you send a text to a mobile phone from Clockwork the handset responds with a delivery status. These are relayed back to Clockwork and can be forwarded to a URL of your choice.

    To configure delivery receipts, login to Clockwork, under the “sending” menu, select “Delivery Receipts”.

  • How do I get delivery receipts?

    Once you’ve logged into Clockwork see under the menu item “sending” you’ll find the option “Delivery Receipts”.

    You’ll need a URL with a listening script.

    You can opt to receive receipts via HTTP or XML and can set up to receive by default or provide a delivery receipt request on each text message.

    There are two requirements for the delivery receipts URL.

    1. The site must be publicly accessible over the internet.
    2. It must return an OK status code when accessed.
  • Can I receive delivery receipts in batches?

    Clockwork lets you receive delivery receipts either one at a time, or in batches.

    If you’re a large volume sender it’s more efficient to receive delivery receipts in batches.

  • Can Clockwork receive text messages?


    You’ll need a Clockwork mobile number or access to a 5 digit shortcode and keyword e.g. HELLO at 84433.

    Just sign up or log in to your account and select Receiving/Add new from the main menu to get started.

  • How do Clockwork mobile numbers work?

    Clockwork mobile numbers are 11 digit UK numbers (07123456789), the same format as a standard mobile number.

    All texts are sent directly to your Clockwork account and can be forwarded to a URL of your choice.

    Anyone who texts in will be charged at their standard network rate for sending to a UK mobile number. For most people in the UK this will be one message off their bundle, those outside the UK will likely be charged at their standard international rate.

    You can set up your Clockwork mobile number by logging into your account and clicking into ‘Receiving’ and ‘Numbers and keywords’.

    Contact us to set up a Clockwork mobile number.

  • Can Clockwork handle shortcodes?

    We can supply 5 digit shortcodes across all UK networks for receiving text messages.

    1. You can either have a dedicated code where all texts sent to the code will be forwarded to you, or
    2. Opt for a keyword on a shared shortcode. Only texts that begin with a specific word will be forwarded to you e.g. HELLO to 84433

    You can setup a shared shortcode by following these steps or contact us to discuss setting up a dedicated code.

  • What's your retry policy if my server is down?

    For those who receive either delivery receipts or texts on Clockwork we have a generic retry policy to prevent us from hammering your servers.

    In summary: the policy is incremental and will stop attempting to send the message or delivery receipt after 72 hours.

  • Can I send a long or concatenated message?

    Yes, you can concatenate up to 3 messages.

    Log into Clockwork and look under “Settings” and then “Validation” to enable long messages.

    To send via Clockwork use the parameter “concat”.

    The character limits per message are:

    • One message – 160 characters
    • Two messages – 306 characters
    • Three messages – 459 characters

    These are technical limits set within GSM standards and hence not variable.

  • Can you filter by IP?


    You can enhance the security on your Clockwork account by only allowing connections from IP addresses you list. Log into your account, select “Settings” and then “IP filtering”. You can then add your IP addresses as required.

  • What's the throughput, how many SMS can Clockwork handle?

    Some clients send one or two messages per day, some send hundreds of thousands in a single broadcast.

    If you batch messages into blocks of 500 and send via 4 threads, you should be able to get 10,000 SMS through in approximately 1 minute 10 seconds, about 373 SMS per second.

    You can read a more detailed discussion of throughput on our blog entitled “Our SMS API is now Twice as Fast”.

  • How much does Clockwork cost?

    Clockwork works on a “pay-as-you-go” basis with messages costing as little as 2p. Prices are per message, per recipient. There are no contracts or commitments, you just pay for what you send. All of our pricing can be found on our pricing page and if you’re sending over 1000 texts per month, get in touch for a quote.

  • Why is there a maximum amount on how much I can top up?

    To help keep your account secure and protect against fraud, we limit the amount that can be topped-up with each transaction. This amount should increase for you with time, but if a higher limit would be useful sooner, don’t worry – just get in touch with our support team.

    Alternatively, you can set up a credit account which means you’ll never run out of credit – we’ll simply invoice for what you use. If you’re sending over 500 texts per month on behalf of a registered company, you can apply to upgrade your account. If this sounds like the right option for you, get in touch and our support team can help you.

  • How do I send international messages?

    When you first sign up for a new Clockwork account, you can send messages to mobile phone numbers in the United Kingdom (+44). If you try to send outside of the UK, you’ll get an error code 15. If you would like to send to numbers outside of the UK, contact our friendly support team to have international sending added to your account. You can see if it’s added already by visiting the ‘International sending’ settings page in the app.

  • Is Clockwork GDPR compliant?

    We did lots of work ahead of GDPR coming into effect in May 2018 to ensure we were as GDPR compliant as possible. Here’s our GDPR blog post. Our long-standing commitment to looking after your data doesn’t stop there, of course – we continue to review and improve what we’re doing. If you have any questions, feel free to get in touch.

  • I have a question you haven't answered

    We’d be more than happy to answer it. Please get in touch and let us know how we can help.