The purpose of this list is to provide basic information about T.38 router and firewall equipment known to work with CallWeaver and, more in general, with SIP devices.

Please use Faxing with CallWeaver as a reference when configuring your T.38-capable device to work with CallWeaver.

Please note that this list is intended to show equipment that has bad implementations (not referring to callweaver in particular).

Most of the bugs are T38-related. In fact, a lot of devices that are natting clients, mangle the SIP payload to automatically adjust the ip and the ports. While this works for RTP, very few implementations knows about T.38. So it may happen that t38 reinvites are badly managed bu the NATTING router and nothing works.

Remember that those routers are very dumb, and changing the ports from 5060 to another one, usually solves the problem.

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