Couple suggestions to be add to the chat room feature in the games if possible (1) Global - it would make recruitment for guild a lot easier (2) Captain room - exclusive to Captain & Quartermasters ONLY where they can discuss matters in secret (3) Private message for individual within the guild - in case they don't want to share with everyone Thanks..
Have the members in your guild download and join a chat app. Several to choose from that is what most guilds here do.
There is also an unofficial global chat room where you can talk to other guilds if you use Slack. http://rov.io/slack to sign up. It's community run, and it has a section where guild captains(or in a couple cases, QMs) can talk to each other. On an iPad you can even pin it side-by-side with the app, to have it run on the side, and chat without leaving the game. Midoki has rejected requests of a global chat before. It would take them hiring more staff members to moderate, and it would honestly just be a stream of a couple dozen guilds spamming "Join Pinoy Guild 37" or whatever, like every single Facebook post currently is.