20 MB is currently the maximum size that can be sent. This is something that is constantly being looked at by our product team. This limit was recently increased from 5MB to 20 MB, but it's still recommended break up larger faxes into multiple smaller faxes. Internet faxing is a bit different in that there is correlation with larger faxes having higher failure rates. This is not something that is specific to RingCentral. If you do an internet search and compare fax size limits with other internet faxing services, you'll see that many set there limits at about 5 or 10 MB because of this. We understand that there are many occasions where larger faxes need to be sent so there is an ongoing endeavor to improve success rates on larger faxes. Perhaps at some point in the future they'll increase the limits again, but there is no ETA at this time.