Meck/SMS & Phone App Guide.md

SMS & Phone App (4G variant only) - Meck v0.9.3 (Alpha)

Press T from the home screen to open the SMS & Phone app. Requires a nano SIM card inserted in the T-Deck Pro V1.1 4G modem slot and an SD card formatted as FAT32. The modem registers on the cellular network automatically at boot — the red LED on the board indicates the modem is powered. The modem (and its red LED) can be switched off and on from the settings screen. After each modem startup, the system clock syncs from the cellular network, which takes roughly 15 seconds.

Key Mapping

Context	Key	Action
Home screen	T	Open SMS & Phone app
Inbox	W / S	Scroll conversations
Inbox	Enter	Open conversation
Inbox	C	Compose new SMS (enter phone number)
Inbox	D	Open contacts directory
Inbox	Q	Back to home screen
Conversation	W / S	Scroll messages
Conversation	C	Reply to this conversation
Conversation	F	Call this number
Conversation	A	Add or edit contact name for this number
Conversation	Q	Back to inbox
Compose	Enter	Send SMS (from body) / Confirm phone number (from phone input)
Compose	Shift+Del	Cancel and return
Contacts	W / S	Scroll contact list
Contacts	Enter	Compose SMS to selected contact
Contacts	F	Call selected contact
Contacts	Q	Back to inbox
Edit Contact	Enter	Save contact name
Edit Contact	Shift+Del	Cancel without saving
Dialing	Enter or Q	Cancel / hang up
Incoming Call	Enter	Answer call
Incoming Call	Q	Reject call
In Call	Enter or Q	Hang up
In Call	W / S	Volume up / down (0–5)
In Call	0–9, *, #	Send DTMF tone

Sending an SMS

There are three ways to start a new message:

1. From inbox — press C, type the destination phone number, press Enter, then type your message and press Enter to send.
2. From a conversation — press C to reply. The recipient is pre-filled so you go straight to typing the message body.
3. From the contacts directory — press D from the inbox, scroll to a contact, and press Enter. The compose screen opens with the number pre-filled.

Messages are limited to 160 characters (standard SMS). A character counter is shown in the footer while composing.

Making a Phone Call

Press F to call from either the conversation view or the contacts directory. The display switches to a dialing screen showing the contact name (or phone number) and an animated progress indicator. Once the remote party answers, the screen transitions to the in-call view with a live call timer.

There are two ways to start a call:

1. From a conversation — open a conversation and press F. You can call any number you have previously exchanged messages with, whether or not it is saved as a named contact.
2. From the contacts directory — press D from the inbox, scroll to a contact, and press F.

Note: There is currently no way to dial an arbitrary phone number without first creating a conversation. To call a new number, press C from the inbox to compose a new SMS, enter the phone number, send a short message, then open the resulting conversation and press F to call.

During an active call, W and S adjust the speaker volume (0–5). The number keys 0–9, *, and # send DTMF tones for navigating phone menus and voicemail systems. Press Enter or Q to hang up.

Audio is routed through the A7682E modem's internal codec to the board speaker and microphone — no headphones or external audio hardware are required.

Receiving a Phone Call

When an incoming call arrives, the app automatically switches to the incoming call screen regardless of which view is active. A short alert and buzzer notification are triggered. The caller's name is shown if saved in contacts, otherwise the raw phone number is displayed.

Press Enter to answer or Q to reject the call. If the call is not answered it is logged as a missed call and a "Missed: ..." alert is shown briefly.

Contacts

The contacts directory lets you assign display names to phone numbers. Names appear in the inbox list, conversation headers, call screens, and compose screen instead of raw numbers.

To add or edit a contact, open a conversation with that number and press A. Type the display name and press Enter to save. Names can be up to 23 characters long.

Contacts are stored as a plain text file at /sms/contacts.txt on the SD card in phone=Display Name format — one per line, human-editable. Up to 30 contacts are supported.

Conversation History

Messages are saved to the SD card automatically and persist across reboots. Each phone number gets its own file under /sms/ on the SD card. The inbox shows the most recent 20 conversations sorted by last activity. Within a conversation, the most recent 30 messages are loaded with the newest at the bottom (chat-style). Sent messages are shown with >>> and received messages with <<<.

Message timestamps use the cellular network clock (synced via NITZ roughly 15 seconds after each modem startup) and display as relative times (e.g. 5m, 2h, 1d). If the modem is toggled off and back on, the clock re-syncs automatically.

Modem Power Control

The 4G modem can be toggled on or off from the settings screen. Scroll to 4G Modem: ON/OFF and press Enter to toggle. Switching the modem off kills its red status LED and stops all cellular activity. The setting persists to SD card and is respected on subsequent boots — if disabled, the modem and LED stay off until re-enabled. The SMS & Phone app remains accessible when the modem is off but will not be able to send or receive messages or calls.

Signal Indicator

A signal strength indicator is shown in the top-right corner of all SMS and call screens. Bars are derived from the modem's CSQ (signal quality) reading, updated every 30 seconds. The modem state (REG, READY, OFF, etc.) is shown when not yet connected. During a call, the signal indicator remains visible.

SD Card Structure

SD Card
├── sms/
│   ├── contacts.txt           (plain text, phone=Name format)
│   ├── modem.cfg              (0 or 1, modem enable state)
│   ├── 0412345678.sms         (binary message log per phone number)
│   └── 0498765432.sms
├── books/                     (text reader)
├── audiobooks/                (audio variant only)
└── ...

Troubleshooting

Symptom	Likely Cause
Modem icon stays at REG / never reaches READY	SIM not inserted, no signal, or SIM requires PIN unlock (not currently supported)
Timestamps show ---	Modem clock hasn't synced yet (wait ~15 seconds after modem startup), or messages were saved before clock sync was available
Red LED stays on after disabling modem	Toggle the setting off, then reboot — the boot sequence ensures power is cut when disabled
SMS sends but no delivery	Check signal strength; below 5 bars is marginal. Move to better coverage
Call drops immediately after dialing	Check signal strength and ensure the SIM plan supports voice calls
No audio during call	The A7682E routes audio through its own codec; ensure the board speaker is not obstructed. Try adjusting volume with W/S
Cannot dial a number	You must first have a conversation or saved contact for that number. Send a short SMS to create a conversation, then press F

Note: The SMS & Phone app is only available on the 4G modem variant of the T-Deck Pro. It is not present on the audio or standalone BLE builds due to shared GPIO pin conflicts between the A7682E modem and PCM5102A DAC.