Will there be any kind of benefits in terms of Asterisk server cpu cost when using softphone opposed to using another type of phone? I suspect this, since coding/decoding is done on the pc on which the softphone is installed and not on the asterisk server. Is this correct?
Yes, I think so; using a softphone on a pc, or a sip/iax2 “hardphone” or an external sip to fxs gateway lower the * server cpu usage, this usage will be higher if there is a pci fxs card in the server to connect analog phones.
If you mean a softphone compared to a sip hardphone, Then no you are not correct, It will make no difference. Compared to a Zap phone, it may make a little difference.
But TBH a sofphone is at the bottom of the pile when it comes to quality