Fax, Modem, and Text Support over IP Configuration Guide, Cisco IOS Release 15M&T - V150.1 MER Modem Relay Support for TDM to SIP Gateway [Support] - Cisco
Huawei HG655b VDSL2 modem/router SIP VoIPx2
SIP ALG: What Is It & Why You Should Disable It for VoIP
How to Disable SIP ALG on Popular Routers
How to configure SIP ALG on your modem | CenturyLink
Speedport W724v Adsl Adsl2+/vdsl2/dsl Optical Fiber Modem/router Sip Voip Dlna+ Nas 802.11b/g/n/ac Home Router - Fixed Wireless Terminals - AliExpress
Vocal's SIP Analog Modem Solutions
AC1200 Dual Band 4G LTE cat6 WiFi Modem SIP Router