The best replacement for sipdroid is csipsimple.

The best alternatives to sipdroid are rated as following:
★★★★★  csipsimple
★★★  linphone
★★★  groove ip
★★  zoiper
★★  talkatone
★  3cx
  bria

Your alternative for sipdroid is not listed? Suggest!
Speaking about sipdroid, one probably shouldn't forget about pbxes.

Other search terms related to sipdroid and their ratings are:
★★★★★ pbxes
★★★ sipgate
You have in mind a companion for sipdroid and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sipdroid in all years. Click on graph for more.
sipdroid
csipsimple
linphone