diff --git a/api/src/gateway/gateway.module.ts b/api/src/gateway/gateway.module.ts
index 34052d6..167bc67 100644
--- a/api/src/gateway/gateway.module.ts
+++ b/api/src/gateway/gateway.module.ts
@@ -5,6 +5,7 @@ import { GatewayController } from './gateway.controller'
 import { GatewayService } from './gateway.service'
 import { AuthModule } from '../auth/auth.module'
 import { UsersModule } from '../users/users.module'
+import { SMS, SMSSchema } from './schemas/sms.schema'
 
 @Module({
   imports: [
@@ -13,6 +14,10 @@ import { UsersModule } from '../users/users.module'
         name: Device.name,
         schema: DeviceSchema,
       },
+      {
+        name: SMS.name,
+        schema: SMSSchema,
+      },
     ]),
     AuthModule,
     UsersModule,
diff --git a/api/src/gateway/schemas/sms.schema.ts b/api/src/gateway/schemas/sms.schema.ts
index 98772ee..348c8f3 100644
--- a/api/src/gateway/schemas/sms.schema.ts
+++ b/api/src/gateway/schemas/sms.schema.ts
@@ -1,6 +1,7 @@
 import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose'
 import { Document, Types } from 'mongoose'
 import { Device } from './device.schema'
+import { SMSType } from '../sms-type.enum'
 
 export type SMSDocument = SMS & Document
 
@@ -8,14 +9,47 @@ export type SMSDocument = SMS & Document
 export class SMS {
   _id?: Types.ObjectId
 
-  @Prop({ type: Types.ObjectId, ref: Device.name })
+  @Prop({ type: Types.ObjectId, ref: Device.name, required: true })
   device: Device
 
   @Prop({ type: String, required: true })
   message: string
 
   @Prop({ type: String, required: true })
-  to: string
+  type: string
+
+  // fields for incoming messages
+  @Prop({ type: String })
+  sender: string
+
+  @Prop({ type: Date, default: Date.now })
+  receivedAt: Date
+
+  // fields for outgoing messages
+  @Prop({ type: String })
+  recipient: string
+
+  @Prop({ type: Date, default: Date.now })
+  requestedAt: Date
+
+  @Prop({ type: Date })
+  sentAt: Date
+
+  @Prop({ type: Date })
+  deliveredAt: Date
+
+  @Prop({ type: Date })
+  failedAt: Date
+
+  // @Prop({ type: String })
+  // failureReason: string
+
+  // @Prop({ type: String })
+  // status: string
+
+  // misc metadata for debugging
+  @Prop({ type: Object })
+  metadata: Record<string, any>
 }
 
 export const SMSSchema = SchemaFactory.createForClass(SMS)
diff --git a/api/src/gateway/sms-type.enum.ts b/api/src/gateway/sms-type.enum.ts
new file mode 100644
index 0000000..7c7203b
--- /dev/null
+++ b/api/src/gateway/sms-type.enum.ts
@@ -0,0 +1,4 @@
+export enum SMSType {
+  SENT = 'SENT',
+  RECEIVED = 'RECEIVED',
+}