MicroSIP, Signal, Zoiper, 3CX, Whereby, CSipSimple, Zulip, Empathy, tSIP, PhonerLite, Linphone, Acrobits Softphone, YateClient, YakYak, DrayTek SIP SoftPhone, Starfish PBX, Sipnetic, MizuDroid, Cloud Softphone, GV Connect, Vodia Networks, Ottspott, Siphon SIP are some alternatives to Telephone.