After normalization and upload procedure the EMCD checks which from the uploaded phone numbers belong to other Vippie users. A user’s registered phone number is stored in api.clients.phone field. The EMCD compares phone numbers from contacts with the numbers stored in phone field in clients table. When a match is found the record in contacts is updated with value 1 in vippie field.

The server keeps the copy of the phone contacts and performs user discovery procedures whenever a new user joins the service. Thus a Vippie user can immediately receive a notification when only his buddy registered in Vippie service.

The server version of the Address Book must be kept in sync with terminal address book (TAB). Therefore every change on the device must be detected and uploaded to the server. When a change is done from within the app the change should be uploaded immediately (assuming internet connection is present). If this is not possible the record has to be kept in a queue and be sent once the connection to the server is restored. When a change is done from some other application the application should upload the record as soon as it detects the change. There is also a special procedure implemented which periodically checks the consistency of both copies.

When the application sends the address book entries to the EMCD contacts.ashx it gets a response with a token. Within next several seconds the application calls the contacts method with the token as a parameter. The EMCD responds with a pending status or with the list of entries which are registered in the platform that is other RCS users. If the address book has a significant size the application divides it in smaller parts and sends one by one.

The server side procedures search the RCS database asynchronously and every found item (an RCS user associated with one of the uploaded items) is then added to the queue which is in turn queried by the client.

When the discovery procedure completes the application shows the RCS capable contacts marked with a special icon and the presence status information.

The list of RCS contacts returned by EMCD comprises pairs of logins and phone numbers. The logins can be same as phone numbers if user registered with the phone number. In other cases they can be usernames or as in non-generic mode, sequential numbers. Therefore the RCS client has to keep the association between phone number from contacts and its login.

New RCS contact

When the EMCD registers a new phone number (with new user registration or when an existing user adds a phone number) it runs a look up for occurrences of the phone number in other users address books. When a match is found in the api.contacts the EMCD sets the api.contacts.vippie field to 1 which denotes that the number is RCS capable and notify the user who owns the entry. The user’s application upon receiving the message marks the contact in the address book as RCS.

The command to set a contact as RCS is sent to the client via SIP MESSAGE, same way as chat messages. The message carrier a system command Contacts add in its body which is processed by the application but not shown to the user. Also the messages which deliver system commands are not sent over PUSH when user is offline. Instead they are put into the deferred messages table and delivered when the user comes online.

The format of the Contacts add command is following:

Contacts add : {"phones":[{"id":1,"n":48502159212,"l":1000000,"os":"ios"}]}

The example shows the command telling the app to add new user under the certain contact from the TAB. The contact is recognized based on the id and the phone number.

Parameters:

id - a contact's id (taken from the TAB and uploaded to the server)
n - phone number
l - login (SIP username)
os - device operating system

On receiving the Contacts add command the app must store the relevant info in the local copy of the TAB.

The Contacts add command is sent to voipswitch through VSServices/sendsms.ashx. Its configuration is described in TODO dodac link do Communication with clients. The use of sendsms.ashx for this function will be deprecated in near future and will be replaced by direct SIP communication between EMCD and voipswitch as it takes place for other system commands already.

The procedure is repeated for all occurrences of the number in api.contacts table, i.e. for each user’s phone book.

New user joined Vippie notification

When a new user joins the service the system besides the system command generates also a text message which is sent to all the users which have the new account in their Contacts. The message is sent on behalf of the user, with its login and display name in the FROM header. Thus a recipient can see the name as it is defined in his Contacts and can respond to the message directly or initiate a call to the sender.

The “User joined” message is sent by EMCD using direct SIP communication with voipswitch. If the recipient is offline the message will be sent using PUSH notification like any other chat message.

If the message does not come even if you have the newly registered number in your contacts you should check the SIP client settings in the EMCD/AppSettings.config. Next, check connectivity from the EMCD server to voipswitch using SIP over UDP which is used for internal server to server communication.

Removing RCS association from a contact

When a user decides to remove his account and stop using the service the EMCD searches for his phone number in all other user's phone books in api.contacts. When a match is found the server sends a system message with Contacts del command so that the application can update the local contacts accordingly.

The format of the Contacts add command is following:

Contacts del : {"phones":\[{"id":3,"n":48502159200}\]}

When the RCS client receives this command it should remove the RCS login assigned to the

contact item with the received id and number.

Flow diagram