diff --git a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
index 7ecf2af9..7ac9d00b 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
@@ -1653,6 +1653,12 @@ class BaresipService: Service() {
 
     fun runCall(uap: Long, uri: String, conferenceCall: Boolean, onHoldCallp: Long) {
 
+        val ua = UserAgent.ofUap(uap)
+        if (ua != null && ua.account.isMobile && Utils.isUssd(uri)) {
+            sendUssd(Utils.uriUserPart(uri))
+            return
+        }
+
         val executeCall = {
             val handler = Handler(Looper.getMainLooper())
             handler.postDelayed({
@@ -2312,6 +2318,47 @@ class BaresipService: Service() {
         updateMobileStatus(status)
     }
 
+    @SuppressLint("MissingPermission")
+    private fun sendUssd(ussdCode: String) {
+        val uap = uas.value.find { it.account.isMobile }?.uap ?: 0L
+        if (VERSION.SDK_INT >= 26) {
+            val tm = getSystemService(TELEPHONY_SERVICE) as TelephonyManager
+            try {
+                tm.sendUssdRequest(ussdCode, object : TelephonyManager.UssdResponseCallback() {
+                    override fun onReceiveUssdResponse(
+                        telephonyManager: TelephonyManager,
+                        request: String,
+                        response: CharSequence
+                    ) {
+                        super.onReceiveUssdResponse(telephonyManager, request, response)
+                        Log.d(TAG, "USSD response for $request: $response")
+                        postServiceEvent(ServiceEvent("ussd response", arrayListOf(uap, request, response.toString()), System.nanoTime()))
+                    }
+
+                    override fun onReceiveUssdResponseFailed(
+                        telephonyManager: TelephonyManager,
+                        request: String,
+                        failureCode: Int
+                    ) {
+                        super.onReceiveUssdResponseFailed(telephonyManager, request, failureCode)
+                        Log.d(TAG, "USSD response for $request failed with code $failureCode")
+                        val error = when (failureCode) {
+                            TelephonyManager.USSD_RETURN_FAILURE -> getString(R.string.ussd_failed)
+                            TelephonyManager.USSD_ERROR_SERVICE_UNAVAIL -> getString(R.string.ussd_service_unavailable)
+                            else -> getString(R.string.ussd_unknown_error)
+                        }
+                        postServiceEvent(ServiceEvent("ussd fail", arrayListOf(uap, request, error), System.nanoTime()))
+                    }
+                }, Handler(Looper.getMainLooper()))
+            } catch (e: Exception) {
+                Log.e(TAG, "Exception sending USSD request: ${e.message}")
+                toast(getString(R.string.ussd_failed))
+            }
+        } else {
+            toast(getString(R.string.ussd_not_supported))
+        }
+    }
+
     @SuppressLint("FullScreenIntentPolicy")
     fun handleIncomingCall(call: Call) {
         val ua = call.ua
diff --git a/app/src/main/kotlin/com/tutpro/baresip/MainScreen.kt b/app/src/main/kotlin/com/tutpro/baresip/MainScreen.kt
index 9769efce..336be445 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/MainScreen.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/MainScreen.kt
@@ -2057,6 +2057,14 @@ private fun makeCall(ctx: Context, viewModel: ViewModel, uriText: String,
     else if (Utils.isAudioMode(ctx,AudioManager.MODE_IN_CALL) &&
             !Call.calls().any { it.ua.account.aor == ua.account.aor })
         Toast.makeText(ctx, R.string.call_already_active, Toast.LENGTH_SHORT).show()
+    else if (ua.account.isMobile && Utils.isUssd(uri)) {
+        viewModel.dialerState.callButtonsEnabled.value = false
+        val baresipService = Intent(ctx, BaresipService::class.java)
+        baresipService.action = "Start Call"
+        baresipService.putExtra("uap", ua.uap)
+        baresipService.putExtra("uri", uri)
+        ContextCompat.startForegroundService(ctx, baresipService)
+    }
     else {
         viewModel.dialerState.callButtonsEnabled.value = false
         var error = ""
@@ -2330,6 +2338,20 @@ fun handleServiceEvent(ctx: Context, viewModel: ViewModel, event: String, params
     val aor = ua.account.aor
 
     when (ev[0]) {
+        "ussd response" -> {
+            if (aor == viewModel.selectedAor.value)
+                viewModel.dialerState.callButtonsEnabled.value = true
+            handleDialog(ctx, ctx.getString(R.string.info), params[2] as String)
+            handleNextEvent()
+            return
+        }
+        "ussd fail" -> {
+            if (aor == viewModel.selectedAor.value)
+                viewModel.dialerState.callButtonsEnabled.value = true
+            handleDialog(ctx, ctx.getString(R.string.error), params[2] as String)
+            handleNextEvent()
+            return
+        }
         "call rejected" -> {}
         "call outgoing" -> {
             val callp = params[1] as Long
diff --git a/app/src/main/kotlin/com/tutpro/baresip/Utils.kt b/app/src/main/kotlin/com/tutpro/baresip/Utils.kt
index 5f190b39..b7adc48d 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/Utils.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/Utils.kt
@@ -370,13 +370,18 @@ object Utils {
     }
 
     fun isTelNumber(no: String): Boolean {
-        return no.isNotEmpty() && Regex("^([+][1-9])?[0-9- (),*#]{0,24}$").matches(no)
+        return no.isNotEmpty() && Regex("^[0-9- (),*#+]{1,32}$").matches(no)
     }
 
     fun isTelUri(uri: String): Boolean {
         return uri.startsWith("tel:") && isTelNumber(uri.substring(4))
     }
 
+    fun isUssd(uri: String): Boolean {
+        val user = uriUserPart(uri)
+        return user.startsWith("*") && user.endsWith("#")
+    }
+
     fun checkUri(uri: String): Boolean {
         return checkSipUri(uri) || isTelUri(uri)
     }
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 717aa2d5..14f4083e 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -633,6 +633,10 @@
     <string name="no_network">No network connection!</string>
     <string name="no_aec">No hardware Acoustic Echo Cancellation!</string>
     <string name="audio_focus_denied">Audio focus denied!</string>
+    <string name="ussd_failed">USSD failed</string>
+    <string name="ussd_service_unavailable">USSD service unavailable</string>
+    <string name="ussd_unknown_error">USSD unknown error</string>
+    <string name="ussd_not_supported">USSD not supported</string>
     <string name="permissions_rationale">Permissions rationale</string>
     <string name="audio_permissions">baresip needs \"Microphone\" permission for voice calls,
         \"Nearby devices\" permission for Bluetooth microphone/speaker detection,