Building missed-call text-back yourself
If you are technical, this is a real option and cheaper than any product. The core is perhaps forty lines: catch the call-status webhook, check it went unanswered, send a text. The tutorials are accurate. What they leave out is everything after the first week.
What the build actually is
Configure a status callback and you receive the outcome of every call.
No-answer, busy and failed are different outcomes, and treating them identically will text people you actually spoke to.
So the text lands in the thread the caller recognises rather than from an unknown line.
The part most builds forget. An inbound webhook with nothing behind it is a customer talking to a wall.
The four things that make it harder than the tutorial
A caller who rings three times in five minutes should get one text, not three. This is the bug every home-made version ships with.
Texting one silently fails, and you will believe it delivered. You need to check the number type and handle the gap.
Ringing a customer who does not pick up will text them "sorry we missed you" unless you filter direction.
Sending at 3am is legal in some places, unwise everywhere, and an honoured opt-out list is not optional.
What it costs to run
Very little in fees — a number and a few pence per message. The cost is your attention: replies arrive at all hours and nobody else is going to answer them. A build that works perfectly and produces twelve unanswered text threads has made your business look worse than saying nothing would have.
When building is the right call
When you already run infrastructure, when your volumes are small, and when you want the messages to do something specific no product offers. Buy instead when you want the replies handled rather than merely received — that is the part which is genuinely hard, and it is not hard for technical reasons.
Frequently asked
Yes, and on Twilio it is close to a weekend project: catch the call-status webhook, decide the call was missed, send a text from the same number.
Deduplicating repeat callers, silently failing texts to landlines, accidentally texting people you rang yourself, and quiet hours plus opt-outs.
Almost nothing in fees. The real cost is that replies arrive at all hours and nobody else will answer them.
When you want the replies handled rather than just received. Receiving is the easy half.