diff --git a/lib/Controller/RoomController.php b/lib/Controller/RoomController.php
index 1f7d9f22152..4c528120ff5 100644
--- a/lib/Controller/RoomController.php
+++ b/lib/Controller/RoomController.php
@@ -2582,12 +2582,26 @@ public function directDialIn(string $phoneNumber, string $caller): DataResponse
 		try {
 			$entity = $this->phoneService->getAccountToCallForPhoneNumber($phoneNumber);
 		} catch (DoesNotExistException) {
-			$this->logger->info('No account found for direct dial-in with number: ' . $phoneNumber);
-			return new DataResponse(null, Http::STATUS_NOT_FOUND);
+			$dialoutPrefix = $this->appConfig->getAppValueString('sip_bridge_dialout_prefix', '+');
+
+			if ($dialoutPrefix === '') {
+				$this->logger->info('No account found for direct dial-in with number: ' . $phoneNumber);
+				return new DataResponse(null, Http::STATUS_NOT_FOUND);
+			}
+
+			try {
+				// Try to find the number with added dialout prefix as a fallback for old sip-bridges
+				// TODO: Log as error in 26, remove fallback and dialout prefix with 27
+				$entity = $this->phoneService->getAccountToCallForPhoneNumber($dialoutPrefix . $phoneNumber);
+			} catch (DoesNotExistException) {
+				$this->logger->info('No account found for direct dial-in with number: ' . $phoneNumber);
+				return new DataResponse(null, Http::STATUS_NOT_FOUND);
+			}
+
+			$this->logger->warning('Found account for direct dial-in only by adding the dial-out prefix. Please adjust the mapping for number: ' . $phoneNumber);
 		}
 
 		$caller = trim($caller);
-		// TODO: Use later and get name from addressbook? $cleanedCaller = $this->phoneNumberUtil->convertToStandardFormat($caller);
 		$user = $this->userManager->get($entity->getActorId());
 		try {
 			$room = $this->roomService->createConversation(
@@ -2603,7 +2617,14 @@ public function directDialIn(string $phoneNumber, string $caller): DataResponse
 			return new DataResponse(null, Http::STATUS_INTERNAL_SERVER_ERROR);
 		}
 
-		$participant = $this->participantService->joinRoomAsNewGuest($this->roomService, $room, '', true, displayName: $caller);
+		$participant = $this->participantService->joinRoomAsNewGuest(
+			$this->roomService,
+			$room,
+			'',
+			true,
+			displayName: $caller,
+			phoneNumber: $caller,
+		);
 		return new DataResponse($this->formatRoom($room, $participant));
 	}
 
diff --git a/lib/Migration/Version25000Date20260918142246.php b/lib/Migration/Version25000Date20260918142246.php
new file mode 100644
index 00000000000..d364dbbefce
--- /dev/null
+++ b/lib/Migration/Version25000Date20260918142246.php
@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Talk\Migration;
+
+use Closure;
+use OCP\AppFramework\Services\IAppConfig;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IDBConnection;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+use Override;
+
+class Version25000Date20260918142246 extends SimpleMigrationStep {
+
+	public function __construct(
+		private readonly IDBConnection $connection,
+		private readonly IAppConfig $appConfig,
+	) {
+	}
+
+	/**
+	 * @param IOutput $output
+	 * @param Closure(): ISchemaWrapper $schemaClosure
+	 * @param array $options
+	 */
+	#[Override]
+	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
+		$dialoutPrefix = $this->appConfig->getAppValueString('sip_bridge_dialout_prefix', '+');
+
+		if ($dialoutPrefix === '') {
+			return;
+		}
+
+		$update = $this->connection->getQueryBuilder();
+		$update->update('talk_phone_numbers')
+			->set('phone_number', $update->func()->concat(
+				$update->createNamedParameter($dialoutPrefix, IQueryBuilder::PARAM_STR),
+				'phone_number',
+			))
+			->where($update->expr()->gte(
+				$update->func()->charLength('phone_number'),
+				$update->createNamedParameter(6, IQueryBuilder::PARAM_INT))
+			);
+
+		$update->executeStatement();
+	}
+}
diff --git a/lib/Service/ParticipantService.php b/lib/Service/ParticipantService.php
index 04bd24d149c..47c7c0615bf 100644
--- a/lib/Service/ParticipantService.php
+++ b/lib/Service/ParticipantService.php
@@ -601,7 +601,7 @@ public function joinRoomAsFederatedUser(Room $room, string $actorType, string $a
 	 * @throws InvalidPasswordException
 	 * @throws UnauthorizedException
 	 */
-	public function joinRoomAsNewGuest(RoomService $roomService, Room $room, string $password, bool $passedPasswordProtection = false, ?Participant $previousParticipant = null, ?string $displayName = null): Participant {
+	public function joinRoomAsNewGuest(RoomService $roomService, Room $room, string $password, bool $passedPasswordProtection = false, ?Participant $previousParticipant = null, ?string $displayName = null, ?string $phoneNumber = null): Participant {
 		$event = new BeforeGuestJoinedRoomEvent($room, $password, $passedPasswordProtection);
 		$this->dispatcher->dispatchTyped($event);
 
@@ -635,6 +635,10 @@ public function joinRoomAsNewGuest(RoomService $roomService, Room $room, string
 			if ($displayName !== null && $displayName !== '') {
 				$attendee->setDisplayName($displayName);
 			}
+			if ($phoneNumber !== null && $phoneNumber !== '') {
+				$attendee->setPhoneNumber($phoneNumber);
+				$attendee->setActorType(Attendee::ACTOR_PHONES);
+			}
 
 			$this->attendeeMapper->insert($attendee);
 
diff --git a/lib/Service/PhoneNumberValidation.php b/lib/Service/PhoneNumberValidation.php
index c1ce47af600..2f44cbe83d7 100644
--- a/lib/Service/PhoneNumberValidation.php
+++ b/lib/Service/PhoneNumberValidation.php
@@ -23,9 +23,7 @@ public function __construct(
 	 * Validate input as a phone number
 	 *
 	 * - Local number: allow
-	 * - International number
-	 *      a. If valid, strip + and allow
-	 *      b. If invalid, throw
+	 * - International number: If invalid, throw
 	 * @throws \InvalidArgumentException When the number is invalid
 	 */
 	public function validateNumber(string $phoneNumber): string {
@@ -46,10 +44,6 @@ public function validateNumber(string $phoneNumber): string {
 			throw new \InvalidArgumentException();
 		}
 
-		if (str_starts_with($standardPhoneNumber, '+')) {
-			return substr($standardPhoneNumber, 1);
-		}
-
-		throw new \InvalidArgumentException();
+		return $standardPhoneNumber;
 	}
 }
diff --git a/lib/SetupCheck/SIPConfiguration.php b/lib/SetupCheck/SIPConfiguration.php
index 6a0611f88e4..c29b433a77e 100644
--- a/lib/SetupCheck/SIPConfiguration.php
+++ b/lib/SetupCheck/SIPConfiguration.php
@@ -48,9 +48,11 @@ public function run(): SetupResult {
 		$query->select('phone_number')
 			->from('talk_phone_numbers')
 			->where($query->expr()->like('phone_number', $query->createNamedParameter(
-				$this->connection->escapeLikeParameter('+') . '%'
-			)))
-			->orWhere($query->expr()->like('phone_number', $query->createNamedParameter(
+				// TODO: Temporary disabled while we migrate to leading `+` for international numbers
+				// TODO: Either to be deleted later or should complain for numbers without it
+				// 	$this->connection->escapeLikeParameter('+') . '%'
+				// )))
+				// ->orWhere($query->expr()->like('phone_number', $query->createNamedParameter(
 				$this->connection->escapeLikeParameter('0') . '%'
 			)));