SMS setup

SMS is the fallback channel — slower than WhatsApp, more expensive per message, but it works on every phone on earth without an app. GCM uses it for two-step verification codes, urgent broadcasts, and reminders to members who haven't given you their email.

Configure it under Settings → Channels → SMS.

Pick a provider

Provider	What it is	Setup	Cost	Best for
Twilio	Industry-standard cloud SMS API	medium	per-message	most churches in US/CA/UK
smsmobileapi	Phone-relay service (your Android phone sends)	low	bundled	global coverage, low volume
Platform default	Shared platform sender	none	bundled in plan	starter / growth tiers

Option 1 — Twilio

Twilio is the standard for SMS in the US, Canada, and most of Europe. You'll need a Twilio account and a phone number provisioned in their console.

You need:

• Account SID — your Twilio account identifier, starts with AC….
• Auth token — from your Twilio console.
• From number — a Twilio phone number you've provisioned (or an alphanumeric sender ID where supported).

Status callbacks

We automatically configure Twilio to POST delivery status updates back to GCM at /channel-webhook?provider=twilio&event=status. No manual webhook setup needed — the URL is sent with every send and Twilio handles the rest. Delivered / failed / undelivered status appears in message logs within a few seconds.

Two-way SMS

If you want members to reply to your texts, point your Twilio number's A MESSAGE COMES IN webhook at /channel-webhook?provider=twilio in the Twilio console. Inbound texts will create conversations just like inbound WhatsApp.

US carrier registration (A2P 10DLC)

US carriers require any business sending SMS to register through the 10DLC program. Twilio walks you through this — expect 2–4 weeks for approval. Unregistered numbers can still send, but with heavy filtering and capped throughput. For high-volume churches, get registered before going live.

Option 2 — smsmobileapi

A relay service: you install an app on an Android phone, and their cloud routes messages through that phone. The phone uses your real SIM, so SMS goes out as if you sent it from your own device — perfect for regions where Twilio doesn't have great coverage, or for churches that already have a dedicated phone for outreach.

You need:

• API key — from the smsmobileapi dashboard.

That's it. The same API key powers their WhatsApp service if you want both channels bundled.

TIP

Set the phone to "Never sleep" and plug it into power. The relay can't send while the phone is offline.

Trade-off: throughput is capped by what your SIM card and carrier let through. Fine for sub-1,000 messages per send, painful above that. Expect 1–2 messages per second.

Option 3 — Platform default

Some plans include a shared SMS quota — the platform sends through its own Twilio account, billed against your plan. Zero configuration. You'll see your monthly quota under Settings → Billing.

Trade-off: the From number is the platform's number pool, not your own. Members won't recognize who's texting them until they read the message body. For most reminder use cases this is fine; for branded broadcasts, bring your own Twilio.

Per-channel features

Once configured, Settings → Channels → SMS lets you control:

• Max recipients per bulk — defaults to 500, raise carefully.
• Merge tokens — {{first_name}} style personalization.
• Two-way conversation routing — inbound texts route to conversations.

Testing the connection

Hit Send test message in the SMS channel settings. We send a "Hello from GCM" to the org admin's primary phone. If it lands in <30 seconds, you're set.

If it doesn't arrive:

1. Check the provider's own activity log (Twilio Messaging Log, smsmobileapi history).
2. Confirm the recipient number is in E.164 format (+18765551234, not 876-555-1234). GCM normalizes numbers but a malformed one in the member record won't work.
3. Check the provider's billing — Twilio in particular pauses sends when the balance hits zero.

SMS character limits

A single SMS is 160 characters of GSM-7 or 70 characters of UCS-2 (if your message includes emoji or non-Latin characters). Longer messages are split into segments — each segment is billed separately.

GCM shows a live character counter as you compose. Keep broadcasts under one segment when possible.

Cost discipline

SMS is the most expensive channel per message. A few habits that keep costs sane:

1. Default to email for non-urgent messages. SMS for time-sensitive only.
2. Use shortcodes in the body — g.cm/event/123 instead of the full URL — to save characters.
3. Set bulk-send quiet hours in Settings → Channels → SMS to prevent accidental 3am blasts.

Cross-references

• SMS messaging — composing and sending texts.
• WhatsApp setup — usually cheaper, higher open rates.
• Conversations — manage inbound replies.