Problem with incoming SMS on landline


I’m trying to receive SMS messages over my land line using a Zap channel. I’ve tested outbound SMS sending and voice calls which work fine over the same Zap channel. I checked all the usual docs/tutorials. Am I forgetting something obvious here?

Here’s my extensions.conf

exten => s,1,Wait(1)
exten => s,n,NoOp(${CALLERID})
exten => s,n,GotoIf($[${CALLERID} = 08183651350]?smsmtrx,${CALLERID},1:internal,100,1)

exten => 100,1,NoOp(“Not A Text”)

exten => _X.,1,NoOp(“Is a text”)
exten => _X.,n,SMS(${EXTEN}|a)
exten => _X.,n,Hangup()

Here’s my console output

-- Starting simple switch on 'Zap/1-1'
-- Executing Wait("Zap/1-1", "1") in new stack
-- Executing NoOp("Zap/1-1", "08183651350") in new stack
-- Executing GotoIf("Zap/1-1", "1?smsmtrx|08183651350|1:internal|100|1") in new stack
-- Goto (smsmtrx,08183651350,1)
-- Executing NoOp("Zap/1-1", ""Is a text"") in new stack
-- Executing SMS("Zap/1-1", "08183651350|a") in new stack
-- SMS TX 93 00 6D
-- SMS RX 94 00 6C
-- Executing Hangup("Zap/1-1", "") in new stack

== Spawn extension (smsmtrx, 08183651350, 3) exited non-zero on ‘Zap/1-1’
– Hungup ‘Zap/1-1’

Thanks for any help you can give me.