Yes.  Mobile accounts are treated as if they are separate trunk and so will need to be migrated also.  You will see that mobile accounts are usually in the format 'b123456@sip.500.uk.com' and which account / DDI this reference relates to can be found on the 'Mobile Accounts' and 'Numbers' tabs.  Migrating a mobile account is just a single step process (refer to Step 2 of Migrating Your Clients' Trunks) as you do not need to amend any PBX settings.