CMS Error: 21 when sending msg from GSM modem to CDMA phone

[rajmathi_mehta]

Hello All,

I get CMS Error: 21 (Short Message transfer rejected), when I try to send SMS from my GSM Modem to any CDMA phones what could be the reason?

Thanks in advance
Rajmathi

[RocketBob]

Does your GSM modem and the service you signed up for support SMS? Can you send an SMS to a GSM phone?

I have found that SMS is unreliable between different service providers, even if both are GSM. This is especially true with pre-paid services; the post-paid (monthly contract) services are more reliable.

[rajmathi_mehta]

Hello RocketBob,

Modem works fine with other GSM phones (able to send SMS) ... Infact I've never had any problem. I have 2 modems, one sends SMS to both GSM & CDMA, with the other I have this problem. So it has to do with the modem I guess ... rather than the Network operator.

Thanks & Regards,
Rajmathi