While roaming on Telcel (Mexico) with a Verizon (US) mobile, it does not appear possible to send SMS, but MMS works reliably.

The phone receives both SMS and MMS while roaming and on home network.

A configuration option to add "Always convert SMS to MMS" would help solve this roaming annoyance, although you may want to warn about potential extra charges (not an issue for this phone and rate plan BTW).

BTW, the root cause is probably IMS related but Verizon's suggested fixes don't work.

Thanks!