WhatsApp or SMS for collections: both, in the right order.
WhatsApp lets you converse, negotiate and collect in the same chat, and in Shimli it reaches a 98% open rate. SMS reaches phones without data or WhatsApp: in Latin America, 72% of people have a mobile line but only 65% use mobile internet. The best collections strategy uses both in one flow: WhatsApp first, SMS where WhatsApp doesn't reach.
Why choosing well matters
- 98%
- open rate of WhatsApp messages in Shimli operationsShimli production results
- +34%
- contact rate in early collections with Shimli agentsShimli results · 2025
- 72% / 65%
- of Latin America's population has their own mobile line, but only 65% use mobile internet: the gap is reached by SMS or callGSMA, The Mobile Economy Latin America 2024 ↗
A collections flow with both channels
This is how they combine in Shimli. Each customer gets the channel that reaches them, and whatever they reply comes back to the same case.
- SMS
- AI agent
- 01WhatsAppThree days before the due dateReminder with an approved template and payment link to the whole portfolio on WhatsApp.
- 02SMSIf the message isn't deliveredAn SMS goes to the same number, with a short link to the payment.
- 03AI agentThe customer replies “I can't pay”The agent understands, checks the balance and offers an extension within your policy, on the channel where they replied.
- 04WhatsAppThe promise is recordedConfirmation on WhatsApp and a reminder scheduled for the new date.
- 05SMSOn the payment dayA short SMS reminder for those who don't open WhatsApp.
The comparison, point by point
They don't compete: each reaches different customers. The table shows what each one is best at.
| Criterion | WhatsAppofficial API | SMStext message |  Both in Shimlione flow |
|---|---|---|---|
| Reach | Anyone with WhatsApp and data | Any phone, even without data | WhatsApp first and SMS where it doesn't reach |
| Converse and negotiate | Yes, with text, buttons, documents and payment links | Short text replies | The agent negotiates on whichever channel the customer replies |
| Open rate measured in Shimli | 98% in Shimli operations | No read confirmation | Delivery and reply measured on the same dashboard |
| Cost per message | Meta's rate by category and country | The SMS provider's rate by country | Each message on the channel that makes sense |
| Requirement for the customer | Having WhatsApp | Just a mobile line | Nothing extra |
WhatsApp and SMS come out of the same Flow Builder in the $139 monthly plan. Messages are billed by Meta or the SMS provider at each country's rate. See pricing
When each one fits
It isn't a contest: they're tools for different problems.
Use WhatsApp to…
- Converse, negotiate and collect in the same chat.
- Send documents, receipts and payment links.
Use SMS to…
- Reach those without data or WhatsApp.
- Short reminders when WhatsApp isn't delivered.
Use both in Shimli to…
- Cover the whole portfolio with one flow.
- Have every reply come back to the same case and agent.
Frequently asked questions
What people ask when comparing.
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